Prop Problems!

[BassYakR]

Setup!

15ft Marshrunner with 40 Tohatsu

They marshrunner has the old shoebox style tunnel.

Boat is very heavy from factory but the deck was also extended along with side gunnels added.

I have tried a 13p prop with some pretty good cup on it. performed great out the hole. But im only able to turn the motor about 4900 rpm. I have a 13p A-Z prop on it now with little to no cupping and i can turn it 5100 rpm but i blow out pretty bad gettin on step.


BTW it runs 33-35mph like this depending on load. usually has 2 ppl and all gear along with full icechest of mostly ice bc i cant catch any fish and 6gal of gas.

Question is.... does anyone have a 10 or 11p prop with some cup in it that i can try out to see what prop i need to buy so i dont spend unneeded money tryn to get it right? Im thinking an 11p with some good cup will work great. Id like to be able to run the motor atleast 5600 rpm at full throttle. You can even come along for the test run and we can pull it off right then.... I do not want to steal your beloved prop i promise. lol
Question is....

[BassYakR]

Heres the boat! shes very heavy

[Patt]

I have an 11 pitch on my 25 4 stroke tohatsu that you can try out. I blow out pretty bad on my 15/48 semi v with a performance tunnel and I'm running a jack plate but I'm wanting to try a higher pitched prop just to see how it would do

[jlincecum]

nice rig

[keakar]

is it as low as it can go or is there any way to lower the motor? my 40hp Nissan had to go down to the last hole to work better. bedfore that I had trouble finding the right pitch and cup as well as having blowout and all that went away when I lowered the motor.

the install book says the cav plate should be 1" BELOW the hull and not even with it like my dealer had installed it.

I know tunnel hulls are a little different but going with the lowest setting solved this issue for my boat but it wasn't as heavy as yours

[CajunChristian]

Pat: You motor has a 10 spline propshaft, his is a 13 spline, won't fit.

[B-Stealth]

Originally Posted by BassYakR

Heres the boat! shes very heavy

Sweet rig, have you gone by Precision Propellor to see if he has any used?

FYI, I run a 17'X38" Stryon Tunnel with Nissan 2 stroke 25.
I have 2 props, a cupped 13P Powertech which is more of my speed prop (30mph) and a cupped 12P Powertech that jumps on plane great with a load.

I'm prob gonna buy a 10P 4 blade prop soon.