heavy load prop question

[kenbob62]

i have suntracker 21 ft 90 hp 2 stroke, strakes, currently using a 13 /75/15 prop but when I have the boat loaded with 6 adults and gear and 1 child getting on plane is almost impossible ,the boat goes over 33 mph with 3 adults but when the whole gang is on board were doin 11 mph plowing water, does anyone have a prop they change to to combat this or is this the nature of the beast? thanks

[NCBOATER]

From my experience when you get over 4 adults plus gear you need the added floatation of a third pontoon. With the 90hp engine, I don't think you have the horsepower to get the straked tubes up on plane, and you may not have enough floatation to get the toons up on plane either. A lower pitched prop will help to get your RPMs up when loaded, but I don't think you will get it on plane loaded heavy with twin straked tubes and the 90hp. I could be wrong, but this is just my opinion. I have a 150hp Yammy and when I have 4 adults and 4 kids plus pulling a tube, I can only get 28mph with twin tubes no strakes. I am planning on adding a 3/4 length center tube hopefully this winter, but we'll see how that plays out. You could probably try dropping to a 13 pitch prop to see what that will do, but it has a lot to do with getting the nose cones out of the water, which requires surface area, floatation, and Horsepower. Hope this helps some.

[Bryden24shp]

I have a prop for every occasion. 4, to be exact! Light loads, heavy loads, speed and 1 4 blade I bought for looks! Not really, its a POS and I need to sell it! But, it does look good!

[rancherlee]

since you have a Merc give a 4 blade Spitfire a shot, I like mine and it gives me enough bite to get up one plane with a 70 hp and 4-5 adults on board. With the right prop you shouldnt have an issue getting up on top with a 90. Mine only has 3 small tubes

[wed]

i have suntracker 21 ft 90 hp 2 stroke, strakes, currently using a 13 /75/15 prop

Reading your text I understand that you are spinning a 13.75 inch diameter prop.

If so, I think it may be too much prop. I have two props that I use on my boat, very similar, but with a 4 stroke. Try a 13.25 prop and see what happens. Also, I do not have much experience with 2 strokes, so, discounting the difference between the 90 2 stroke and 90 4 stroke, I use a 13.25 X 17 for light loads and a 13.25 X 15 for heavier loads. I can get my boat up on strakes with 6 adults with either prop but it is really difficult with the 17 pitch prop. Also, I find that my boat is really sensitive to trim and even more so with heavier loads.

Hope this helps. Good luck.

[kryptonite]

Pontoon's usually like 3 blade, large diameter, and extra cup.

I'm at 22' with a 75 four stroke, running a 14 x 11p extra cup for heavy loads. I have a spare cheap solas that's 13.75 x 13p that I can turn with a light load, however it doesn't perform as well as the 11p extra cup.

So I'd say try a 14x13p

Also a question, How many RPM's were you at WOT with that heavy load?
How many RPM's at WOT with a light load?

[Drago]

I have a prop for every occasion. 4, to be exact! Light loads, heavy loads, speed and 1 4 blade I bought for looks! Not really, its a POS and I need to sell it! But, it does look good!

So Bryan, do you only use the great looking 4 blade when towing the boat around