Hey Mike, thanks
You are recomending a lower pitch prop. That should help launch the boat out of the water. How are these guys getting away with large pitch (29 or 30)?
Yep, macs are a pain sometimes.

They are able to use a larger prop probably because the boat is lighter or they have more horsepower or both. Also the Kaama came with a couple of different ratios, mine were over driven somthing like 10%. And the Twin Disc tranny had a ratio of 1.54, I think, so my ratio at the prop was about 1.35 There are many factors that affect what size prop you can turn.

Did you make major modifications to the engines or just freshen them up? I you are makeing a lot more power 100 hp + per side maybe you could go to a 27 or so. I think a 30 is just to much.
You are trying to get a lot of mass moving with a lot wetted surface.

It looks like I am going to have to send the manual one page at a time. Let me know if you get the first page and can print it. I will then send the rest.

mike

Mike,
I think these started out as 375 KAAMA packages , although it doesn't make much sense considering the Base parts in this engine. All components are LS6. During a freshen up, Heads were apparently modified, alum roller rockers, pretty wild roller cam (roughly 580 to 590 lift custom iski), advertised as new rods and pistons but I have not torn down the short block enough to confim. 500 HP is advertised by previous owner and it makes sense. 100 HP gain is possible here. I didn't consider the trans having a gear ratio change. Would Formula use different gear ratios in different boats do you think? That F357 is about 2000 lbs lighter than this boat and pushes lots more horsepower at 700 plus per side.

Al,

I doubt that Formula would change the tranny ratio but I wouldn't be surprised if the drive maybe a little different. The drive ratio should be on the serial number plate. Or you can do the spin the input shaft and count the output shaft rotations. Spin the intput shaft 10 times.

That 357 has a lot more power and is much lighter than you are but he is still spinning a four blade prop with lots of diameter, which will help him plane.

If your boat had 375 hp engines from the factory and was spinning a 24, then I think a 27 would be about right. Remember these are big props with thats of surface area and are hard to turn. The twin disc tranny will suck up at least 100 hp at speed also.

I think I would lean toward proping to plane vs. proping for top speed. Also if you have a hard time planing in calm water it will never plane in rough water, unless maybe the waves are coming from astearn and you can "surf" it on plane.

mike

Hey Katdrvr,
Thanks for all the help on the manual. We got the whole thing. Would have been nice if she read my email describing what was coming her way before she read yours and got confused. Alls well that ends well. I owe you a beer or two. Maybe at the Shooters shootout in august. I think a bunch of us from chicago are going down there. I should be on plane by then I hope.

No problem. The whole email thing was kind of funny. I should have played it up a little more. Let me know if you have any questions.

mike