Post by: 78Southwind on December 08, 2014, 06:26:53 PM
Post by: 78Southwind on December 08, 2014, 06:45:56 PM
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Post by: GT Jets on December 08, 2014, 07:13:32 PM
I had a used spare A/B impeller I bought years ago and Chris said the detail work looked good on it so I decided to throw that in to save a few bucks.
(Attachment Link) (Attachment Link)
Be sure to smooth out the transition on the key. You can see where that one was burning the blades.
GT
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Post by: 78Southwind on December 08, 2014, 07:29:23 PM
Be sure to smooth out the transition on the key. You can see where that one was burning the blades.
GT
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Yeah, Chris said he would clean up what little needed to be done to it.
Post by: jyeager on December 08, 2014, 07:35:39 PM
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Post by: 78Southwind on December 08, 2014, 07:39:06 PM
Starks the man when it comes to pump work. He really knows his stuff and will explain everything to you. 👍👍👍👍👍
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Yeah, he spent a lot of time with me explaining everything. Seems like a really good guy.
Post by: 78Southwind on December 08, 2014, 07:43:42 PM
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Post by: 78Southwind on December 08, 2014, 08:35:24 PM
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Post by: 78Southwind on December 08, 2014, 09:02:12 PM
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Post by: 78Southwind on December 22, 2014, 11:24:50 PM
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Post by: jyeager on December 23, 2014, 10:06:01 AM
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Post by: 78Southwind on December 23, 2014, 10:03:15 PM
[attachimg=1][attachimg=2]
Post by: JARVIS on February 18, 2015, 03:52:50 PM
Post by: 78Southwind on February 21, 2015, 11:03:55 AM
what was the machining for on impeller side of bowl?
Chris didn't do any machining to the impeller side of the bowl he only machined the exit side. However the previous owner of the bowl shortened it before I bought it to build pressure.
I am not sure what you a referring to but the suction was machined. Here's a picture of the wear ring being line bored.
[attachimg=1]
Post by: 78Southwind on February 21, 2015, 11:20:16 AM
[attachimg=1][attachimg=2]
Post by: GT Jets on February 21, 2015, 11:25:04 AM
We tested the Southwind at Topock since the water was too shallow in Bullhead. The pump is bad ass and the I dig the inducer there's no cavitation at all. However, the smaller droop didn't help the WOT porpoise at all.
(Attachment Link) (Attachment Link)
Is it a fast bounce, or slow and sort of lazy?
Where is the plate at angle wise?
GT
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Post by: 78Southwind on February 21, 2015, 11:28:56 AM
Is it a fast bounce, or slow and sort of lazy?
Where is the plate at angle wise?
GT
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It's a fast bounce that goes away with more weight in the boat or in a nice 6" wind chop. The plate is at 2*.
Post by: GT Jets on February 21, 2015, 11:35:26 AM
It's a fast bounce that goes away with more weight in the boat or in a nice 6" wind chop. The plate is at 2*.
I would try raising the plate a degree or two. Do you have video of it running?
Up seems counter intuitive, but I have a thought that it's fighting itself. Let it fly a little.
GT
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Post by: 78Southwind on February 21, 2015, 11:44:50 AM
[attachimg=1][attachimg=2][attachimg=3][attachimg=4]
Post by: 78Southwind on February 21, 2015, 11:51:56 AM
I would try raising the plate a degree or two. Do you have video of it running?
Up seems counter intuitive, but I have a thought that it's fighting itself. Let it fly a little.
GT
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I have pretty much already tried all of that years ago. I will see if I can find some video or pictures later.
Post by: GT Jets on February 21, 2015, 11:54:07 AM
I have pretty much already tried all of that years ago. I will see if I can find some video or pictures later.
Does the engine Rev a tiny bit as it falls,or is it really steady? In other words, are you losing bite?
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Post by: 78Southwind on February 21, 2015, 12:19:33 PM
Does the engine Rev a tiny bit as it falls,or is it really steady? In other words, are you losing bite?No rev at all nice a steady.
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Post by: 78Southwind on February 21, 2015, 01:22:44 PM
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Post by: 78Southwind on February 21, 2015, 01:30:57 PM
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Post by: GT Jets on February 21, 2015, 01:50:50 PM
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Post by: 78Southwind on February 21, 2015, 01:53:50 PM
Post by: GT Jets on February 21, 2015, 01:56:04 PM
Same deal. It actually rides better all the way up but scrubs MPH. I also gain 100 RPM with the diverter all the way up.
That would be the pump leaving the water. Or cavitation as I call it.
Do you know where the COG is?
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Post by: 78Southwind on February 21, 2015, 02:06:11 PM
That would be the pump leaving the water. Or cavitation as I call it.I don't personally know cog but when Tom Papp reset the pump 10 years ago he also moved the motor a couple inches forward. I have quarter stringers so it's moved up as far as it can be moved.
Do you know where the COG is?
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Post by: JARVIS on February 21, 2015, 02:52:43 PM
Chris didn't do any machining to the impeller side of the bowl he only machined the exit side. However the previous owner of the bowl shortened it before I bought it to build pressure.
I am not sure what you a referring to but the suction was machined. Here's a picture of the wear ring being line bored.
(Attachment Link)
sorry, thats what i was referring to....thanks. dunno why i said bowl.... :screwy:
Post by: GT Jets on February 21, 2015, 05:20:45 PM
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Post by: 78Southwind on February 21, 2015, 05:55:59 PM
Do you have access to a full droop?Those pictures are with a full droop. I went to a place droop thinking it would help and it didn't.
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Post by: 78Southwind on February 21, 2015, 05:57:53 PM
Do you have access to a full droop?
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Post by: GT Jets on February 21, 2015, 05:59:23 PM
Those pictures are with a full droop. I went to a place droop thinking it would help and it didn't.
Can you borrow am HTP straight?
I feel your problem is upstream, would love to measure some stuff.
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Post by: 78Southwind on February 21, 2015, 06:17:23 PM
Can you borrow am HTP straight?No, I don't? Tell me what to measure.
I feel your problem is upstream, would love to measure some stuff.
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Post by: GT Jets on February 21, 2015, 06:19:46 PM
Trim angle to high causing the too much bow lift for the available thrust to support.
A rocker (aka convex) in the bottom of the rear if the hull, this does not give enough surface for the pump to push against. This can include disturbances before the pump and on the intake of the pump itself
Incorrect weight distribution for the set up. Try moving stuff around a little.
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Post by: 78Southwind on February 21, 2015, 06:48:53 PM
My understanding is that the Southwind's just have to much lift. The center most strakes end half way through the intake and all the strakes are large.
Post by: GT Jets on February 21, 2015, 06:54:46 PM
My understanding is that the Southwind's just have to much lift. The center most strakes end half way through the intake and all the strakes are large.
The super hillbilly fix would be to put a small kick on the outside strakes, I think 5/16" X 2" long would be more than enough. You could use Bondo as an experiment.
GT
Post by: 78Southwind on February 21, 2015, 08:03:41 PM
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Intake
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Post by: 78Southwind on February 21, 2015, 08:06:12 PM
Post by: 78Southwind on February 21, 2015, 08:20:03 PM
Post by: GT Jets on February 21, 2015, 08:39:57 PM
Inner most strake.
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Do the outer strakes go all the way to the transom?
I would wedge them. Your pump is leaving the water looking at the far away teeny tiny cell phone video... LMAO
GT
Post by: 78Southwind on February 21, 2015, 08:58:46 PM
Post by: GT Jets on February 21, 2015, 09:08:51 PM
Yes they do go all the way to the transom.
It sounds stupid. but I would take a little Bondo and put a couple of little wedges on the very back of the strakes on the outside. Probably two inches long and no larger than about 5/16" think at the back, tapered. It will not cost you any speed at all. It may even improve speed if you can get it to settle down. :-\
Is there anything weird in front of the pump intake?
GT
Post by: 78Southwind on February 21, 2015, 09:11:33 PM
It sounds stupid. but I would take a little Bondo and put a couple of little wedges on the very back of the strakes on the outside. Probably two inches long and no larger than about 5/16" think at the back, tapered. It will not cost you any speed at all. It may even improve speed if you can get it to settle down. :-\No nothing weird that I can think of.
Is there anything weird in front of the pump intake?
GT
Post by: GT Jets on February 21, 2015, 09:20:56 PM
No nothing weird that I can think of.
I could tell you what we did to our Southy, but then I would have to have you killed...LOL
We have a 1978 with a Small block, extensive bottom changes, does a little over 60 with a small block Chevy, shooting for 70 MPH, I have the impeller out and we are making some carburetor changes tomorrow. What I really want to do is put some headers on it, but the grey guy wont let me... :thumbdown:
But seriously, there was a weird bump in front of the intake at the keel line, no idea what was being done, it was similar to a spoon. But wider and shorter than what I have seen in the past. Our ride plate is right at 3° up and has a full droop with a race nozzle and butt bucket. We used a flat shoe, but the intake is at 3°.
The bottom is speed coated to about 7' forward, but that should not really change the handling characteristics. Buy a quart of Bondo and try it, worst case scenario is you sand it back off....
Bet it fixes it... 8)
GT
Post by: 78Southwind on February 21, 2015, 10:15:56 PM
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Post by: GT Jets on February 21, 2015, 10:24:18 PM
Looking at this picture, it looks as though it has that odd hump before the intake.
And is that ice cream on the loader? Lmao.
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Post by: 78Southwind on February 22, 2015, 12:12:25 AM
But seriously, there was a weird bump in front of the intake at the keel line, no idea what was being done, it was similar to a spoon.
GT
Interesting...When I bought my Southwind 26 years ago the intake was set further in the hull and it had that weird little bump. At that time the boat did about 63 MPH but after all the mods (engine and pump) 10 years ago I picked up 12 to 15 MPH but I also picked up the porpoise at WOT.
Post by: 78Southwind on February 22, 2015, 01:40:56 AM
Have you/can you put a straight edge across the keel and see where everything is? Like the height of the loader ramps, the difference in ejection of the shoe relative to the keel, how straight the keel is in front of the intake.
Looking at this picture, it looks as though it has that odd hump before the intake.
And is that ice cream on the loader? Lmao.
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If I have time before I leave I will try to put a straight edge to it, otherwise I will do it next time I make it up. The hump/bump isn't really there any longer. No, it's a rats nest...no just crap from the river water. lol
Post by: 78Southwind on February 22, 2015, 02:35:33 AM
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Post by: 78Southwind on February 22, 2015, 02:46:58 AM
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Post by: angermgmt on February 22, 2015, 07:55:29 AM
B
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Post by: 78Southwind on February 22, 2015, 10:05:03 AM
Hey Jerry how long is your ride plate ?About 13.5" from the transom and 19.75" from where it bolts to the shoe.
B
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Post by: 78Southwind on February 22, 2015, 03:34:50 PM
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Post by: GT Jets on February 22, 2015, 03:43:13 PM
I really didn't see anything on the bottom that stood out as a problem but there is a little 5200 sealant on the bottom I should sand off.
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This is going to sound stupid, but I would drop the shoe even further.
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Post by: 78Southwind on February 22, 2015, 03:58:28 PM
Post by: GT Jets on February 22, 2015, 04:08:00 PM
With the shim installed the porpoise was even worse.
Do you have any nozzle wedges? I would put about 6° of up wedge in, not necessarily get more up trim, but raise the thrust line. See what it does, good or bad. I hate that intake install. .
Thinking it might be worthwhile to reset it. Yuck.
GT
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Post by: 78Southwind on February 22, 2015, 04:18:07 PM
Do you have any nozzle wedges? I would put about 6° of up wedge in, not necessarily get more up trim, but raise the thrust line. See what it does, good or bad. I hate that intake install. .I hear ya on the intake. I think I might have 6* of wedges at home. I am running 2* now.
Thinking it might be worthwhile to reset it. Yuck.
GT
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Post by: Flusher on February 22, 2015, 04:20:10 PM
Post by: 78Southwind on February 22, 2015, 04:23:54 PM
What is your shutdown like? Crazy?Not crazy but Not good. It's better without the shim but still worse than the old shoe.
Post by: angermgmt on February 22, 2015, 06:01:48 PM
About 13.5" from the transom and 19.75" from where it bolts to the shoe.
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I have turnbuckles on my plate and mis adjusted them at one point and it porpoises like no ones business. Made a couple of turns to the buckles and all fixed. Maybe think about changing to an adjustable component instead of the fixed.
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Post by: 78Southwind on February 22, 2015, 06:08:51 PM
I have turnbuckles on my plate and mis adjusted them at one point and it porpoises like no ones business. Made a couple of turns to the buckles and all fixed. Maybe think about changing to an adjustable component instead of the fixed.The plate is set at 2* and I have shims to change it.
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Post by: GT Jets on February 22, 2015, 06:11:13 PM
I have turnbuckles on my plate and mis adjusted them at one point and it porpoises like no ones business. Made a couple of turns to the buckles and all fixed. Maybe think about changing to an adjustable component instead of the fixed.
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FYI, it is a shim type, I use the same ones.... You simply add/subtract aluminum shims to adjust. Takes out human error...
GT
Post by: angermgmt on February 22, 2015, 06:25:11 PM
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Post by: angermgmt on February 22, 2015, 07:35:24 PM
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Post by: jet fever on February 22, 2015, 07:55:53 PM
He got it home we took it out that damn thing would porpoise like a mofo.
Got it home 180 the wedge - didn't do anything
He replaced the chevy window motor (the berk e trim motor)
Then went from jetovator to PD nozzle and tried different trim tabs
long story short never fixed the issue had kids sold the boat would have been nice to have cured it. At one point he sucked a valve into the original block and the piston chewed it up. Built a 498 had a screaming motor in a lake boat that couldn't ride right. Oh well cant wait to read how you cure yours.
Post by: TrollerDave on February 22, 2015, 08:47:23 PM
I am pretty sure I am just going to have some cavitation plates made. I know they worked for BN, SouthwindSal and Squirtcha. I lost my pictures I had of BN's cavitation plates that Jack @ MPD built for him (Thanks to the old Hotboat Meltdown) but I was able to find Squirtcha's set-up.
(Attachment Link)
I think Dan (Sqirtcha) said that after straightening the bottom on his Kachina, the cav plates were the only thing that helped his porpoising issue.
If I remember right, he tried everything.
In the 3rd pic of the last series, it looks like there is a small gap between the keel and the straightedge, right in front of the intake.
Would this cause any issues with the ride? If it affected how the pump was loaded, could that affect the ride?
Post by: 78Southwind on February 22, 2015, 09:05:53 PM
Yeah, I remember the post back on Hot Boat in fact I was the one that gave Squirtcha? the picture of Flyin Brian Neal's (*BN*) cavitation plates so he could copy them. However, he ended up getting some for free off of a buddy's boat. I just can't find the pictures I had of them since the old Hot Boat meltdown so I put up Dan's set up (they both had Southwind type bottoms). Dan put the plate down by 1/8" and Brian 1/16".
I talked to Chris about it when I picked up the shoe to see if he worked with Jack back when *BN* was trying to figure out his porpoise. He said he did and remembered Brian's boat and he said they must of tried 7 or 8 different combinations of things and could never get it to settle down until they used the cavitation plates. I think Brian gained about 6 MPH (went from 88 MPH to 94 MPH) after installing the plates. Here's a picture of his boat at Ming before the plates.
I am no expert but I didn't notice anything that looked bigger than a 1/16" and I don't think that would cause the dreaded Southwind porpoise.
Post by: 78Southwind on February 22, 2015, 11:49:22 PM
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Post by: jyeager on February 23, 2015, 08:06:30 AM
Post by: 78Southwind on February 23, 2015, 10:50:43 AM
has stark talked to you about moving the motor forward any? That may help too.I have quarter stringers so there's not a lot of room left to move the engine. It was already moved foreward an inch or two when Tom Papp installed the rail kit.
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Post by: MPKardell on February 23, 2015, 03:02:21 PM
Post by: GT Jets on February 23, 2015, 06:36:04 PM
Once you have the right shape figured out, simply glass over it with finish cloth and tinted resin.
GT
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Post by: 78Southwind on March 16, 2015, 07:45:20 PM
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I am not sure what happened maybe I explained it wrong but when Chris and I talked I told him that I wanted the plate to be somewhere between 1/16" to an 1/8" down. I was pretty surprised that I had lost so much MPH (I thought I might lose a couple or break even) so I measured the hook created by the plate and it's between 3/16" and a 1/4". Not much of a big deal since I wanted to get the pieces powder coated anyways. So Chris said he would be happy to make it to my specs with no additional charge.
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Post by: 78Southwind on March 16, 2015, 07:58:00 PM
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Post by: jet fever on March 17, 2015, 11:13:08 AM
Post by: jet fever on March 17, 2015, 11:16:31 AM
Post by: jyeager on March 17, 2015, 01:13:52 PM
Wish we could see the loader metal angle. I bet if you alter the shape you could pick up more mph
I seriously doubt it. I not surprised to see a loss in MPH. If you were on the track i bet you would see a big gain in E.T.
MPH doesn't mean crap IMO.
Post by: jet fever on March 17, 2015, 01:40:24 PM
Post by: jyeager on March 17, 2015, 01:49:47 PM
Well If I lost 5mph Id try to find a loader with a arc to put as much water into the area as possible so I knew I was getting as much force from my pump as possible. Could be wrong but just a suggestion. Ride is better but Id want to gain the speed back and that pump has alot of goodies alreadyIt's a good idea. But, if you put a more aggressive loader into the boat then you run into over charging problems. The only real way to know what's going on is to tap the intake and bowl for pressure. witch I am sure Chris has talked to him about.
Like I said. He may have dropped MPH but the boat most likely is quicker all around with the plates like that.
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Post by: Flusher on March 17, 2015, 02:38:11 PM
There is a compromise to the performance gains. Once you start going faster, the shutdown becomes more dangerous.
Post by: 78Southwind on March 17, 2015, 02:47:18 PM
Squitcha? (Dan) posted that he ended up at 1/8 down on the cavitation plates and it cured his problems. However, he never GPSed his boat after the installation so who knows if he gained, lost or broke even.
I have only GPSed my boat at the river until this last test. I usually ran 78 MPH down river and 72 up river. So I figured that the current must of been around 3 MPH giving me an honest 75 MPH speed. When I tested at Lake Elsinore last week it ran 70 MPH. So that's where I am getting my data. I am probably going to run it at the river before I make the changes.
I am trying to only make one change at a time so i won't make any other changes until the plates are machined and then I will go from there.
With all that said, what are your guys opinions of getting the plates closer between 1/16" to 1/8" of down? I would think that it would create less drag allowing the boat to ride on less wetted area. Possibly finding a happy medium between ride quality and speed.
Post by: 78Southwind on March 17, 2015, 03:43:14 PM
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Post by: Flusher on March 17, 2015, 03:43:22 PM
I calculate that if I machine the water surface of the angle, I could take it down another 1-1.3 degrees which would equate to .052-.068 up at the trailing edge. From there, the surface against the transom can be angle cut to achieve approximately .052 per degree. I think 2-2.5 degrees off the transom side would be about the maximum I could remove without thinning the material too much.
The decision to error on the safe side while still effecting a positive change was made.
Respectfully submitted,
Joe
Post by: 78Southwind on March 17, 2015, 04:12:09 PM
My reply was really an attempt to address the loader comment and not to question your testing methods. I'm not trying to stir the pot and no disrespect intended.
I calculate that if I machine the water surface of the angle, I could take it down another 1-1.3 degrees which would equate to .052-.068 up at the trailing edge. From there, the surface against the transom can be angle cut to achieve approximately .052 per degree. I think 2-2.5 degrees off the transom side would be about the maximum I could remove without thinning the material too much.
The decision to error on the safe side while still effecting a positive change was made.
Respectfully submitted,
Joe
No disrespect taken, the post wasn't intended as a reply to you but rather me thinking out loud and looking for some comments about my thought process and hoping I was right. I am not even sure if I am measuring right compared to where Brian and Dan were measuring. Don't get me wrong the ride is awesome just looking to pick up some of the speed that was lost. Can you calculate what the hook would look like with those cuts?
Post by: Flusher on March 17, 2015, 04:42:42 PM
Can you calculate what the hook would look like with those cuts?
Running some quick numbers, it looks like I can reduce it by approximately .164. Forgive me for being conservative, but I am concerned about going too far. Might be able to squeeze a little more out of it without thinning the material too much.
Post by: 78Southwind on March 17, 2015, 05:37:29 PM
Running some quick numbers, it looks like I can reduce it by approximately .164. Forgive me for being conservative, but I am concerned about going too far. Might be able to squeeze a little more out of it without thinning the material too much.
If I am understanding you right then it should be perfect. If the hook is 1/4 (.25) and you reduced it by .164 the hook would be .086. That's pretty close to the middle of 1/16 (.0625) and 1/8 (.125). Which was my goal. I will see if I can get some calipers in there to get a more precise measurement.
Post by: 78Southwind on April 02, 2015, 08:14:57 PM
I don't know if you got my PM. I don't know if we are talking the same thing since I don't know what to call it other than "hook" and I don't know the math but what I did is measured the hook that was created by the tab. I couldn't get any calipers in there so I put a straight edge on the hull and the tab and came up with a little over 3/16" of a hook. I wanted it to be somewhere between a 1/16" ( 0.0625) to a 1/8" (0.125) hook. Chris and I agreed that 0.100 would be our goal. Let me know if I am being clear.
Post by: Flusher on April 02, 2015, 08:24:57 PM
Post by: 78Southwind on April 09, 2015, 02:34:56 PM
(https://www.socaljetboats.com/proxy.php?request=http%3A%2F%2Fimages.tapatalk-cdn.com%2F15%2F04%2F09%2F5835aa160f1874298c114da801ca1406.jpg&hash=80d779aec10faca870f7ae65f1aae711cee168a4)
(https://www.socaljetboats.com/proxy.php?request=http%3A%2F%2Fimages.tapatalk-cdn.com%2F15%2F04%2F09%2F531ef14fa01c9f477bc930126682c9aa.jpg&hash=e615cf3b752e5ca3cbc069280c20002547ecbc40)
Post by: loweryjennifer on April 09, 2015, 02:41:33 PM
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Post by: 78Southwind on April 09, 2015, 02:46:32 PM
Looks nice. 👍Thanks
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Post by: jimpen on April 09, 2015, 07:00:31 PM
I got my tabs back. They look bitchen.. Just a heads up most guys run slower at Elsinore I have heard 3-5 mile per hour. This has something to do with the water
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(https://www.socaljetboats.com/proxy.php?request=http%3A%2F%2Fimages.tapatalk-cdn.com%2F15%2F04%2F09%2F531ef14fa01c9f477bc930126682c9aa.jpg&hash=e615cf3b752e5ca3cbc069280c20002547ecbc40)
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Post by: 78southwindtdeck on April 09, 2015, 07:43:03 PM
Post by: 78Southwind on April 09, 2015, 07:52:32 PM
. Just a heads up most guys run slower at Elsinore I have heard 3-5 mile per hour. This has something to do with the waterLol well I guess I should have GPS'd it at Parker.
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Post by: bbfsouthwind on April 09, 2015, 07:54:34 PM
Post by: jimpen on April 09, 2015, 07:54:38 PM
Lol well I guess I should have GPS'd it at Parker.. Yes sir unless you base test was there you got notta
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Post by: 78Southwind on April 09, 2015, 08:00:52 PM
How far is your motor from the transom? I am have a 18' v bottom southwind with a 800+hp 545, I have moved the motor forward a few Inches.Moving the motor was the first suggestion but I have quarter stringers and with the current setup I have I can't really go much more forward.
Post by: 78Southwind on April 09, 2015, 08:05:21 PM
. Yes sir unless you base test was there you got nottaWell maybe I didn't lose any speed at all. Jason and I were playing around a little bit at Parker and his boat does 80 and I ended up about three quarters of a boat length ahead of them. But I'm also running an inducer and he's not.
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Post by: bbfsouthwind on April 09, 2015, 08:15:40 PM
Post by: 78Southwind on April 09, 2015, 10:02:24 PM
I was just wondering because i have not ran my boat yet. But I have converted mine to full stringer.
Let's us know how it works out once you get her wet. 8)
Post by: bbfsouthwind on April 10, 2015, 07:39:16 AM
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Post by: loweryjennifer on April 10, 2015, 11:44:59 AM
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Post by: 78Southwind on April 10, 2015, 10:27:48 PM
Jerry we will run both boat at the next run with gps with only u and Jason in them. 🚤💨No I think we'll leave you in the boat that way I will win for sure.
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Post by: loweryjennifer on April 10, 2015, 10:33:39 PM
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Post by: 78Southwind on April 10, 2015, 10:46:12 PM
It may be a little while before it gets wet, have a baby girl on the way and buying a new house! I am entertaining rigging up a set of cav plates before I get the boat finished up. I have most of the hardware except the plates themselves. I had b1 do all the pump work, so it'll be a runner when it's done. Are you running a droop or a straight snoot?It's the place HPH.
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Post by: bbfsouthwind on April 11, 2015, 08:21:20 AM
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Post by: 78Southwind on April 11, 2015, 12:18:06 PM
I never really had an issue with porpoise before I pulled mine apart, but it had a stock 460, I did flip it but I didn't change the bottom at all I just repaired anything that wasn't perfect and smoothed the intake entry. I am curious to see how mine will act as I set my pump back a few inches to where the hand hole cover is half in half out of the boat. I have a shoe, ride plate setup. Lots of good info In here, I hope you get yours ironed out!
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I don't remember a porpoise issue when it was a 60 MPH boat either. However, when I increased the HP a little bit it started porpoising. It's not really bad until the speed catches up to the RPM. I just think the hull was designed as an efficient hull for stock power. I don't think Southwind thought that boaters would be putting big power in them especially when they have quarter stringers (though I have heard the earlier 18's had full stringers but I have never seen one). There's a lot of lift with the large strakes and the center most lifting strakes ending halfway through the intake. If you look at a CP the strakes are much smaller but the innermost strakes do go all the way to the transom. If you look at the Rogers, Hallett and Bahner hull the innermost strakes all end before the intake.
What is interesting is that the Miller hull has a bottom very similar to the 18 Southwind. There is a really nice black and blue 81 Miller out there that had big power (900 HP) that ran really good but did have a hop out on take off but it didn't really seem to porpoise. Chris at B1 did the pump and Todd at TRG did the bottom. I wondering if the bottom had a 1/16 to 1/8 hook in it to cure the porpoise deal.
I have been reading about the Southwind porpoise issue for years and have collected information about it over the years. Here's a couple things the pros have been saying:
Jack at MPD posted that with the Southwind hull you should leave 1/16" to 1/8" of hook near the back of the hull. He said these hulls like it.
Jeff Bennett posted that the Southwind and all of its derivatives are very good boats, but often porpoise. That problem gets worse as speed increases, so that high horsepower versions are especially difficult to deal with. This means from my perspective what the hull needs is more than a blueprint, but a modification, which is substantially more difficult. Greg Shoemaker and I came up with a combination that resolved the Southwind porpoise last year that involves both a hull modification as well as a bolt-on change (Cavitation Plates). If you are going to work on the bottom, you might as well get it right on the first shot. Because of the complexity of this job, you might consider giving Greg a call.
Post by: 78Southwind on April 11, 2015, 12:28:30 PM
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Post by: jet fever on April 11, 2015, 12:55:26 PM
I'd slap a stockish used motor in it and Punt it away go drop motor is different Hull.
My buddy had built 496 in his Dont matter when it rode like shit and your knees slap the dash. I hated riding in that thing. Now I know why he couldnt get it to quit the damn Hull was never gonna let it settle down. Weak
Post by: 78Southwind on April 11, 2015, 06:39:50 PM
Geez. Your a better man than me.I hear ya. This was my first boat that I bought back when I was 20. That was 26 years ago so it has a little syntamental value to me. But if I was to do it all over again I would just buy a tunnel and be over with it.
I'd slap a stockish used motor in it and Punt it away go drop motor is different Hull.
My buddy had built 496 in his Dont matter when it rode like shit and your knees slap the dash. I hated riding in that thing. Now I know why he couldnt get it to quit the damn Hull was never gonna let it settle down. Weak
Post by: 78Southwind on April 11, 2015, 06:45:57 PM
Post by: jet fever on April 11, 2015, 06:56:06 PM
Post by: 78Southwind on October 27, 2016, 12:53:13 AM
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