Back before I found SCJB, I thought my boat was OK. But now I have "speed envy." I need your opinions on what might be "wrong". Here's what I know and don't know:

I bought the boat and used it the summers of '96 & '97. It is a 1976 Apollo, which is probably a splash of a splash of a splash. I have attached a picture of what the shape of bottom looks like. 18' long. Just weighed it and with full gear, 1/2 full gas tanks but no crew it is 2,100#. For those two seasons, the boat was "stock" with the motor all the way back against the pump. All I used it for was skiing and tubing the kids. 3,000 rpm = 30-32mph. 4,000 rpm = 40mph. BBF (don't know what cid 429/460 I assume.) Fuel tanks are in the front. Hull always rode "wet" with the spray coming off about 1' behind the driver.

Then I moved to San Diego for 6 years and never used the boat the whole time. It sat in storage and eventually flooded full of rain water. So when I moved back to OR, I ripped everything out down to the shell, took all wood and foam out - and started from scratch. I changed a bunch of stuff about the layout - I moved the motor forward 20" and changed the seating arrangement. I replaced my jetovator with a PD. Trim angle will have about a 2mph impact good or bad depending on the position. But "best" speed is with only 1 notch up from neutral.

OK, now the boat handles EXACTLY the same as before motor relo. Still doing the same speed at the same rpm. Spray still comes off the hull at about the same location. In other words, moving the motor cg didn't really help or hurt the ride. Based on everything I read online, I would have thought this would have ruined the ride but it wasn't good even with the motor in the "correct" location. Also, I measured the distance from keel bottom to bowl CL and it is 8". I have checked for hook as best I can and I do not believe I have any but it's not something I look at every day.

Never had the pump apart so I don't know what cut impeller or what condition everything is in. Yesterday I found an ad for my same boat (except stock - no whupass on the rigging) on Craigslist and the guy is claiming it will do 60-70 mph but I'm taking off 10mph just because it's crackslist talk. Still - I'm starting to think that either:

a) my pump has serious issues
b) my pump CL is way too high above keel and I need to redo intake or go to a droop
c) my hull sucks.

I would like to do an honest gps 50mph at 4,000-4,500 rpm and I would be happy. Doable?

You moved your motor 20"s forward???  I thought two inches was a big jump lol.

Honestly, that hull just isn't a big performer or top speed hull. I would move the motor back where it was, so you can fit as many people as possible and gear, and have fun with it. And then after some money saved go out and buy a "performance" hull if you want to go fast

I don't know chit about your hull, but you should be able to do 50 with a fairly stock motor and get there pretty easy(tight jet, good tune ect.). Part of the reason peeps do pump setbacks is tho move the weight(engine) back. Putting the motor back would be wise IMO.

X2.

First lesson I learned on here, and I think it was Terry that pointed it out, jet boats like the "Junk in the Trunk".

Ray

Thanks for the ideas so far - keep them coming!

Just to clarify - the boat did the same thing before I moved the engine. I agree that engine and fuel location is important for high speed boats - like 60+mph. But I'm just trying to get to 50 and I am committed to leaving the motor where it is at.

And the motor will spin higher than 4k, I just don't go there. I want the boat running and can't afford to trash an engine.

FYI - moving 600#'s of motor forward 20" on a boat with a total weight of 2100# only changes the cg location by about 3-5" (you have 1500#'s left with the weight distributed more or less evenly). I know that once the hull gets high enough up out of the water this 3-5" can make a big difference, but I have a lot of hull still down in the water so I don't think cg location is the culprit. (I'll get a couple of people sit in the back (either side of the motor) and if cg is the issue I should see a little bit of speed improvement.

I am more focused on what hasn't changed which is 1) hull shape, 2) pump condition, and 3) thrust axis. Somebody mentioned this isn't a "performer" hull but it doesn't look much different from any other "good" hull below the water line. I know this hull will never be a "fast" boat I just want 50mph. If a 20+' cruiser hull can get over 40mph on a stock BBF then I'm thinking this hull can hit 50 it just has something else wrong.

Is 2100# a reasonable weight for an 18' boat? I think my hull bottom is laid up like 1/4"-3/8" average. And is 8" height between pump CL and keel bottom typical?

I think I need more info - gotta find out what's inside the pump.

If memory serves these were "short decked" (not dicked)  boats,
GT

Just shy of 8' from tip of bow to steering wheel.

"Just for fun" I just measured where the cg is now: 68-69" forward of keel/transom intersection.

Thanks for the ideas so far - keep them coming!

Just to clarify - the boat did the same thing before I moved the engine. I agree that engine and fuel location is important for high speed boats - like 60+mph. But I'm just trying to get to 50 and I am committed to leaving the motor where it is at.

And the motor will spin higher than 4k, I just don't go there. I want the boat running and can't afford to trash an engine.
FYI - moving 600#'s of motor forward 20" on a boat with a total weight of 2100# only changes the cg location by about 3-5" (you have 1500#'s left with the weight distributed more or less evenly). I know that once the hull gets high enough up out of the water this 3-5" can make a big difference, but I have a lot of hull still down in the water so I don't think cg location is the culprit. (I'll get a couple of people sit in the back (either side of the motor) and if cg is the issue I should see a little bit of speed improvement.

I am more focused on what hasn't changed which is 1) hull shape, 2) pump condition, and 3) thrust axis. Somebody mentioned this isn't a "performer" hull but it doesn't look much different from any other "good" hull below the water line. I know this hull will never be a "fast" boat I just want 50mph. If a 20+' cruiser hull can get over 40mph on a stock BBF then I'm thinking this hull can hit 50 it just has something else wrong.

Is 2100# a reasonable weight for an 18' boat? I think my hull bottom is laid up like 1/4"-3/8" average. And is 8" height between pump CL and keel bottom typical?

I think I need more info - gotta find out what's inside the pump.

FWIW Steve, the pump does not even make peak thrust until abou 4400-4600 RPM, which should not hurt it inb the least, just burn a tad more fuel.

GT

I would be surprised if it is anything special. We need a Ford expert to tell me what typical HP for a plain BBF would be.. 300? 350?

That RPM doesn't surprise me then... a stocker 460 won't turn much at all. Sorry, I thought you were going for high speeds, not just a decent speed lol... Move the motor back to where it was, get a good tune up in, and have fun... just my .02 cents