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Messages - Stevecat

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301
Hulls / Re: Intake Side Fins - Cut 'em Off!
« on: December 07, 2008, 06:57:32 PM »

the pivot point moves at different speeds and different centers of gravity,


I agree with this. The pivot axis location depends on how much of the hull is wetted or down in the water. At slow speeds there is a lot of hull in the water and the pivot point is as far forward as it will get. Think of your hull as a giant, blunt weird shaped fin. As you increase speed and the hull starts to plane then less wetted area and most of it further back, so now the pivot point shifts rearward. And as you get ultra fast and start flying the hull like Beerjet always does, then there's very little hull in the water and the pivot point is way back at or near the intake area.

All of what I just said is b4 adding turning fins/skags up in front of the pump inlet. When these are present, then the pivot point will "cling" to their location, because they become the fulcrum for the turn in stead of the hull itself.

302
Hulls / Re: Intake Side Fins - Cut 'em Off!
« on: December 06, 2008, 02:08:02 PM »
Anyone cut them off and had it be BAD????

303
Hulls / Re: Intake Side Fins - Cut 'em Off!
« on: December 06, 2008, 08:42:29 AM »
Each boat & setup is different of course, but each has it's own turn axis (an imaginary line vertical out of the boat where it pivots in a turn). Most boats turn axis will be forward of the pump inlet. Maybe a few boats have the axis farther back - somewhere near the inlet. Mine is well forward - probably 2-3 feet. (I'm rigged more like a competition ski boat.)

For a boat with turn axis at or near the inlet area, those fins never see any side/cross flow, so in my opinion they are un-necessary for this setup and can be cut off (or left alone) without ever noticing a difference.

But for most boats (including mine) where the turn axis is forward, then as you turn, these fins start to get a portion of flow across them instead of straight at them. In a hard turn, this cross flow will go turbulent and this will get sucked into the pump. In other words you will cavitate your pump. That is exactly what happened with my boat. Because my turn axis is so far forward I would get it even in a mild turn and the boat speed would fall off dramatically. (My setup is just a more extreme case of turn axis.)

So I took a deep breath last Spring and put a fresh blade in the sawzall. One of the best moves I've made. Now I can turn as hard as I want (& I mean real hard) and no cavitation whatsoever.

For a flattie or other hull with nothing on the bottom to keep it from sliding sideways, the pump inlet fins are too small and in the wrong place. Turning fins are the correct thing as is discussed in some other posts.

And this same phenom comes into play with certain loaders and certain rock grates. The slight cross flow in a turn (which is natural and unavoidable) will hit the side of the loader/grate and go turbulent. Some loaders take this into account and others don't.

304
The No Wake Zone / Great YouTube of a guy landing a plane with only 1 wing
« on: December 05, 2008, 06:39:31 PM »



Notice the name of the plane  :)

If that guy raced boats I bet he could take on that Jesus dude from the motivational posters.


305
The No Wake Zone / Re: Help! Confused new guy...
« on: December 04, 2008, 07:09:32 PM »
Grew up with a 78 28' Hawaian Daycruiser 454 Berk, and it would do 55 with all our gear and 3 adults. Our record from Long Beach to Catalina in fair seas was just under 30 minutes.

s..sss....salt water?!!  :sly: Eeewwww!!

306
Projects / Re: Pantera Resto
« on: December 04, 2008, 12:04:05 PM »
we do not know what the long term effects of these new resins are.

So that's why my pecker stopped working and my kids have gills!  :sly:

307
Jet Pumps / Re: rudder on a berkley pump
« on: December 04, 2008, 08:26:27 AM »
Have a stock Berk rudder. Always thought is was useless but reverser linkage fastens to it so there it is. Boat still wanders all over at slow slow speeds. X2 what Tom says. The gas pedal steers a jetboat.

308
Projects / Re: Pantera Resto
« on: December 03, 2008, 08:43:32 PM »
Years back I was driving from San Jose to Santa Cruz one PM (when I was doing damage inspections full time) ALAS !! I spied a rectangular red box along side the freeway , I pulled over and risk life and limb to throw it in the back of my Colt There it was a SAWZALL  (without regard one of the best tools I have in my arsenal ) .

I always wondered what happened to my sawzall.  :'( Last time I saw it was when I laid it on the roof of my truck. :screwy:

309
Jet Pumps / Re: Jet Pump Dyno
« on: December 02, 2008, 01:40:46 PM »
OK I have been thinging about it and I think the only way to get some kind of idea on how your pump is working is to get some data on the lake. Get RPM / intake preshure, GPS / RPM, Nozzel Velocity / Manifold preshure, I don't know, then take the engine out and run it on a dyno and try to recreate the runs on the water.  This would give you an idea of the pump efficiency at different points allong the engine's power curve and might tell you when it drops off due to internal problems.  Then swap pumps and do the same thing noting all the similarities and differences between the pumps.  Have a few beers and figure out why one is better or worse than the other. It will probably come down to water conditions or the quality of the beer. Or it might figure out a way for a jet boat to break the sound barrier with 150 horses, who knows.

An alternate way is to have a big HP motor with VFD. First you spin your jet dyno through 0-5000rpm without any load and jot down motor amp draw vs shaft speed. This will give you no-load power consumption.

Then you bolt on your jet pump unit to this imaginary dyno rig. Pump is just out to the bowl, no diverters or steering shit. This discharges into a sensor pipe. All you really need is two pressure ports on either side of a slight orifice. From those two pressure readings you can get a lot of shit. You could also have a pitot tube or two just for fun. What you want is to calc hydraulic power of the jet exhaust. With these two points of info - input HP (at the shaft) and jet hydraulic power you can figure out pump efficiency. I bet it's actually quite shitty. Probably around 85%. From there you play and make changes. You don't need flow viz even though it would be fun to have everything clear just to watch the fish swim by. But the end goal is just to make changes that increase pump efficiency. It's all about max mass flow per input HP. The amperage measurement can be very accurate so it will detect slight changes in pump performance.

310
Jet Pumps / Re: Jet Pump Dyno
« on: December 02, 2008, 01:26:48 PM »
Hey Stevecat, I think we're on to something here ::) There seems to be a common denominator, guess I better keep my eyes open for a good used motor and VFD??????

GT

Yeah find us a cheap 500HP with VFD, then about 800 ft^2 facility with a BIG main breaker panel, good water and a floor drain. And I think we need a 2.5:1 speed increaser with good quality gears.  :o

311
Jet Pumps / Re: Jet Pump Dyno
« on: December 02, 2008, 12:51:05 PM »
The Berk guys were probably gods for their day. They had to do shit the hard way. By pencil, paper, intuition and then a lot of prototype work makin chips. But they could not have got it all right. Like Wiz says, there are too many variables. Like most of us, I think I know enough to be dangerous. And when I look at an impeller and see straight leading edges and relatively simple "airfoil" shapes, I'm pretty sure there's more to be had. Just look at a Hamilton impeller.
http://www.hamiltonjet.co.nz/includes/files_cms/file/JetTorque%2011.pdf (and go to page 2)
Much more complex shape. They are probably the only OEM to do modern computer analysis of a pump system. But they don't seem to be into racing...

And look at anything designed in the 60's compared with it's modern counterpart. Airframes, jet engines, auto engines, bridges, buildings. It's all changed. Anyways, maybe there are some improvements to be had and maybe not. But a dyno with accurate measurements and repeatable results would go a long way to helping rig a boat properly.

And like GT says, there are two things a jet dyno could do: 1) allow you to either match the pump exactly to the motor you built, or the other way. 2) maybe after running several makes/models of pump with all the various tricks and shit we do today, we might discover that there are some more tricks lying around. I suspect that's how fuel injection got adopted, or blowers, turbos, blah blah.

312
Jet Pumps / Re: Loader Removal
« on: December 01, 2008, 03:23:16 PM »
They are straight slot stainless bolts and when I went to turn them, they twisted the end of my screwdriver. Thats why I double nutted it from the top and broke two of them loose that way. Tomarrow I will get a screwdriver with a 1/2" blade or grind a chisel down to fit. Maybe one of those impact screwdrivers that you hit with a hammer might do the trick. I put some penitrating oil on today, so hopfully that will help too.

Same ting for me ;D I had broke ones too. Do what Brad sez. Carefully drill out the centers with drill bit no bigger than ID of threads. OK if you are off center a bit. Then EZ out or pry the shell of the screw out. Then drill out the old threads and put in 3/8 or 7/16 through bolts with self lock nuts. Spooge a wad of silicone in the hole as you put the bolts in.

PS there is nothing more exciting than drilling your first hole in the bottom of your boat!!!!

313
Engine Mechanical / Electrical / Re: Burnt exhaust gaskets
« on: December 01, 2008, 10:50:56 AM »
Thanks everyone for the advice! OK Tom I will call about the gaskets after I weld and powder coat them and am ready for install.

314
Project Boats For Sale / Re: Rare!!! '74 Laveycraft 20' Mini Daycruiser
« on: December 01, 2008, 09:32:17 AM »
New! Lower price and more pics!!! :o

$1250 for the hull only. Add $250 for the pump. Add $250 for the trailer. Add $500 for the Olds 455 V8.

315
The No Wake Zone / Re: I found a job - Winterizing a 460
« on: November 25, 2008, 09:56:57 AM »
Up is up in this picture. This is the left side rear. It's the little brass threaded plug to the right.

316
Hulls / Intake Side Fins - Cut 'em Off!
« on: November 25, 2008, 04:12:18 AM »
3AM and I'm reading old posts... I'm addicted :screwy:. Ran across this comment from Bottom Feeder:

"I know you So Cal types would never think about removing the side fins on you intake  ;D But that is a good place to start. They have an effect on the roll center and dont do much for loading. The worst part is the placement. If you run a forward skag and the skags on the pump you have one fighting the other. Think about it the way it is. The forward skag is your pivot the nozzel is your force and direction. With the fins on the intake the pivot and fulcrum are way to close together."

This guy knows his shit. I cut mine off (B4 reading this thread) but he is dead on. Those things don't make any sense. I can't see any upside to em, but lots of downside. They are in the perfect place to dork up handling or (in my case) block flow to the pump in a hard turn. I think they musta looked good on paper back in the 60's when Berk made their castings. But IMO they are a mistake.

How many of you out there have removed them? Did you do it with a saw or just use the bottom of the lake? >:D Anybody got ideas about what good they do?

317
Engine Mechanical / Electrical / Burnt exhaust gaskets
« on: November 24, 2008, 02:12:43 PM »
This is after just one season. Burnt sides were up. What did I do wrong? I have a BBF, logs and snails. Log bolts were torqued to 40 ft-lbs I think. Too loose? Wrong gaskets? Warped log faces?


318
Gelcoat / Paint / Fireberglass Repair / Re: Bondo
« on: November 24, 2008, 11:06:33 AM »
It's not modeling clay  ;D

It's made to be spreadable for only a very short time. 

If your trying to build up an area for shape you need to make it out of something srtonger than Bondo.

Get us some pics of what you're trying to do and maybe we can help.

I have two project where I need/want something less gooey than bondo and with a longer working time:
1) On my boat I have made a whole bunch of interior layout changes. My motor cover is a 1-off with a bunch of big corner fillets . It went well, just took friggin forever cause I had to do one face at a time and mix little blobs of bondo every 5 minutes. Now I've got the whole rear area to do. It's all cosmetic nothing structural (backsides are glassed).

2) My trailer is covered with some kind of bondo/filler put on by the factory to make it look smooth and sexy. Now I have "personalized" it by chopping out some length. I want to finish up these weld areas with whatever filler/bondo they used to make it all look clean.

319
Gelcoat / Paint / Fireberglass Repair / Bondo
« on: November 24, 2008, 07:46:33 AM »
I've been using the red stuff. I need something that doesn't kick so quick. I see the green stuff in pics and on TV. Is is different/better than the red? What should I use for fairing that I can work with for like 20 minutes? Thanks.

320
Engine Mechanical / Electrical / Re: Can I Powder Coat Logs?
« on: November 24, 2008, 07:41:02 AM »
Thanks for the advice so far guys. Looks like there is both ceramic powder and now a high temp regular powder, so I'm gonna go ahead.

B4 I coat the logs I want to weld them to my snails. I want to get rid of the joint and clean up the look a bit. Has anyone welded theirs? Got any advice?

321
The No Wake Zone / Re: Rant Warning! I'm Against Big3 Bailout - Here's Why
« on: November 22, 2008, 12:36:55 PM »
Feel free to agree or disagree with my position. But whatever your feelings, let your senator know.

Here's the link to their contact info. It's fairly easy to fill out their email forms.

http://www.senate.gov/general/contact_information/senators_cfm.cfm

Just say something simple like: "I am for/against bailing out the US auto industry."

(Or feel free to borrow from my rant if you want.)

322
The No Wake Zone / Rant Warning! I'm Against Big3 Bailout - Here's Why
« on: November 19, 2008, 06:14:02 PM »
There are two "players" in my saga of Detroit: The past and present leaders of the Big Three car companies and the past and present leaders of the UAW. I am going to refer to these people collectively as "management" in my discussion.

For over 30 years of my adult lifetime I have watched the leadership of Big Three automotive ignore the realities of the marketplace. It doesn't matter what the excuses are, the absolute bottom line is they have mismanaged their business and the evidence is massive loss of market share. The Asian car companies have kicked their ass. They are still kicking ass and they will continue to kick ass. This is called free market capitalism - nothing more, nothing less. After 300 years of trying various systems, free market capitalism seems to succeed where socialism, communism, dictatorships and monarchies have failed. Free market capitalism has determined that Detroit's Big Three don't have a clue and they are being punished for their faults.

And for 30 years, the same group of people who have failed to react effectively to worthy competitive products has also stood by and allowed their businesses to enter into unsustainable union contracts. Again, when I refer to management I mean the management of both the UAW and the Big Three. Together, they have committed industrial suicide. I can assure you that BOTH groups of management knew at some level that they were negotiating themselves into ruin. But oh boy, the UAW had a nice ride there for about 30 years! God bless 'em for their moxy and egocentric, short-sightedness. They obtained great pay and benefits for their members. (I am indeed jealous.) But there was a consequence to their actions - they created a cost structure that could not be sustained. The combination of high wages for active workers, together with growing pension fund obligations for retirees, topped off with declining sales due to crappy products is NOT a formula for success.

Good job UAW management and legal consul - you made yourselves a LOT OF MONEY and had a good time! But isn't your job as grown-up, supposedly responsible professionals to balance both the short and long-term health of the business? And shame on you Big Three management! What the hell were you thinking as you kept signing the contracts? The collective behavior of these two groups of management borders on fraud. They promised their workers pay and benefit packages that were in NO WAY sustainable for the long haul. Over on Wall Street this is called a Ponzi scheme.

In the real world of most tax payers, this kind of behavior can only go on for a couple of years and we're out of business. The only places where this level of insanity exist without consequence are in Detroit, the US health care industry and any big, fat, heavy-public-sector, socialist country like France.

So now, after 30 years of stupid decisions, slow-motion suicide and egoistic wages and benefits, Detroit management (including union management) want Mommy and Daddy to make it all better. They want our government to make the bad monster go away so they can keep having fun! I say what any parent has to ultimately learn to say if they want their kids to grow up - sorry Big Three and UAW, but NO.

The US is supposed to be a democracy with a free-market economy. I don't want the US to turn into France (one is enough thank you).

323
Projects / Re: 1975 Bayon
« on: November 17, 2008, 08:09:38 PM »
I got to get it done in time for that Potholes Reservoir bash that I just found out that I missed this year. :banghead:

U and me both ;)

324
The No Wake Zone / Re: This really sucks
« on: November 17, 2008, 11:12:50 AM »
Hang in there Glasscutter. Just get though each hour and each day for awhile. We're here for you in whatever way we can help.

325
Engines / Engine Parts For Sale / 1974 era Hardin Marine Olds 455
« on: October 28, 2008, 07:48:59 AM »
Hardin Marine engine - probably 1974 (same year as boat it came out of). Block casting #396021Fa and "K" Heads. Eldebrock intake. Starter, flywheel, distributor. Also has a Holley carb not shown in photos.

$750

Steve 503-957-6954

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