hydrofoil

[bigbass55]

hey guys i just took the stingray hydrofoil off my 1992 40 hp evinrude to see how it performs without it....it is ok to run the engine with the holes unfilled on the cavitation plate where the hydrofoil was mounted?...im getting 27 mph at 5200 rpm with the hydrofoil on...its on a tx 17 basstracker fishing boat turning a new 12x15 vortex prop

 

[Silvertip]

Re: hydrofoil

The engine should rev in the 5600 - 5800 range and even 6000 won't hurt it. I had that engine on a similar sized boat running a 13SS, 15AL, and 17AL props and the engine was happiest with the 15. As it is, you are lugging it and two-strokes don't like that. Check the position of the AV plate. You might try raising the engine mounting a hole or two -- just don't go so high that you lose water pressure. RPM and speed should come up. You can epoxy the holes closed. Put tape over the bottom of the hole and fill with epoxy.

 

[bigbass55]

Re: hydrofoil

is it ok to run the motor a time or two without the holes filled for testing purposes?. the cav plate is about 1/2 in. above bottom of boat....rpm is with 2 men, full gas, batteries and all gear.. thanks guys

 

[bigbass55]

Re: hydrofoil

bump ^

 

[Dhadley]

Re: hydrofoil

The holes should be no problem, especially for testing. Have fun!!

 

[bigbass55]

Re: hydrofoil

im considering going to a ss prop. what size and brand would you guys reccomend for my setup? thanks in advance

 

[bigbass55]

Re: hydrofoil

bump

 

[bigbass55]

Re: hydrofoil

i took the boat out 2day without the hydro foil and if the conditions were right i squeezed 28 mph out of her a 1 mph faster difference but the rpm stayed the same at around 5200 (the most i could get out of it). the engine is already 1 hole up and i dont think 1 more hole would make a lot of difference in rpm and speed. should i drop down i pitch maybe try a ss prop? what do u guys think?

 

[walleyehed]

Re: hydrofoil

That 1 hole can make from 75-150 RPM difference...don't be afraid to test it...just do it 1 hole at a time...

 

[bigbass55]

Re: hydrofoil

ok so best case scenario i get 5350 rpm outta her by goin up 1 more hole....better than now i kno, but ive been told she needs to run in the 5600-5800 range...what reasonably priced ss prop would put me in that range and not sacrafice any topend....i would love to gain sum tho 8) thanks guys

 

[Dhadley]

Re: hydrofoil

Max out the set up you have now, then consider switching props.

 

[steelespike]

Re: hydrofoil

I believe the motor developes its power at 5,000 rpm
At 5350 you wouldn't be to bad but you need to fine tune the trim before going to a prop.Verticle trim could net 2 or 3 mph.Angle trim could net some more.You should go to the prop forum to select a prop.Size for size The stainless will be more efficient thus you would go down
in size some especially to gain rpm.You may be able to go higher with the verticle trim after you go stainless.

 

[bigbass55]

Re: hydrofoil

ok i raised more hole and it vented terribly and i got bout 100 rpm more so i think im better where i was....what size ss prop do u guys think would work best for me...im unsure about the rpm change between ss and aluminum....maybe a 12 x 13 or 12 x 11?. what do u guys think...how about a rapture prop they have em on here for 154 bucks sounds like a deal to me...maybe i could still raise her 1 more hole with the ss prop...thanks guys

 

[Crownie2]

Re: hydrofoil

ok i raised more hole and it vented terribly and i got bout 100 rpm more so i think im better where i was....what size ss prop do u guys think would work best for me...im unsure about the rpm change between ss and aluminum....maybe a 12 x 13 or 12 x 11?. what do u guys think...how about a rapture prop they have em on here for 154 bucks sounds like a deal to me...maybe i could still raise her 1 more hole with the ss prop...thanks guys

I'm thinking the 12 x 13 would be low enough to go, even SS. You could be right about the height - try it withe the SS. Where is the anticavitation plate now in relation to the bottom of the boat?

Good Luck!

Bob

 

[walleyehed]

Re: hydrofoil

Alot of misunderstandings here...
First, the Horsepower was taken at 5000RPM for standards of BIA/NMMA...doesn't mean anything about where the engine "Likes" to run.

100RPM gain is BY NO MEANS venting bad, and, a bit more cup will fix that asap.
The 13P may have enough lift to get a few more than the usual RPM and get ya closer to where you need to be.

 

[bigbass55]

Re: hydrofoil

how do you feel about the 11 pitch prop walleyehead?

 

[bigbass55]

Re: hydrofoil

the anticav. plate is about 3/4 above bottom of the boat

 

[Crownie2]

Re: hydrofoil

the anticav. plate is about 3/4 above bottom of the boat

3/4"? That should be high enough - is that one hole up or two? If it is the latter and you were experiencing blowout, yes go back to the first hole up.

 

[Crownie2]

Re: hydrofoil

how about a rapture prop they have em on here for 154 bucks sounds like a deal to me...maybe i could still raise her 1 more hole with the ss prop...thanks guys

IMO - the 13" Rapture sounds really good for $154!!

Bob

 

[bigbass55]

Re: hydrofoil

i think im gonna get the rapture but cant decide between a 11 and 13 pitch....any thoughts?