Prop suggestions

[Groo]

I am completely new to power boating, but here now since a pontoon boat came with the new house.

It is a 1990 22' twin toon with a manual height adjust for the outboard. I assume because of the motor being held by an adjustable linkage contraption instead of solid mounted, the boat is rated for only 75hp, or maybe that is just because it is a pontoon? The place is on a river with a large shallow spot between the house and the more major river, so the depth adjust is useful, but of course if I lift it up much, I can't give it much throttle and it handles like crap.
It is loaded pretty good whenever we go out, just based on the size and number of people in the family...a bit over 1000lbs in live weight plus all the gear at a minimum is a fair assumption. It is rated to hold quite a bit more (2375lbs IIRC).
It has a real weak engine for the size of the boat; Evenrude 28spl. (which is apparently a 30hp motor with no bells or whistles?)
The prop (now in need of replacing, found a couple rocks yesterday) is a 012030, that looks like a 9.25x12. When I go through the on-line prop selectors (using 28hp), that is the most aggressive prop for that engine. The mildest suggested looks to be a 9x9.
Am I correct in thinking I should be closer to the 9x9 with this large boat? I am inclined to try a 9x10.
It certainly isn't going fast, so the slip must be significant or it is bogged way down below what it is supposed to be running
I have no tach on this boat.

anything that I can do to get it to maneuver better in general?

 

[Sea Rider]

Without a tach that combo goes dead, buy a Hardline induction hour/tach model HR-8061-2, check Iboats, Amazon. Install it and report max wot rpm achieved as usually will be loaded. With a correct prop maximization toon will perform much better than now.

Happy Boating

 

[Groo]

I am not quite sure what "Without a tach that combo goes dead" means.
Even if I had a tach; I couldn't accurately test WOT RPM now. It needs a prop. I would certainly entertain putting a tach on it with a new prop, but I need a new prop regardless. It doesn't make sense to buy one that I suspect is incorrect for the application.

 

[ondarvr]

Without knowing RPMs and other details, the 9" is more likely to work better, but either one will be better than the current one.

​Best bet would a 4 bladed high thrust prop, but you may have to search a little harder for one.

 

[Sea Rider]

That's why it's imperative to tach factory delivered prop with OB, will know if performed right or not. If so, in the event it's broken can buy exact same new or go to a less pitch prop in case OB needs to rev higher. It's near impossible to dial best prop for your application on first try if previous prop was not tached as to go from there.

Anyway will need to spend some cash in pursuit of best prop for your application running an underpowered OB which needs to rev between middle to max wot revs. Any prop you choose will be your starter prop...

Happy Boating

 

[ahicks]

A pontoon is not the best handling boat available, especially when dealing with wind and currents, and even more so if you're forced to run the engine real shallow to clear the sand bars! My bet is you'll develop more a lot more skill when it comes to handling the boat as the season progresses.

For your situation, I like the 9x10 plan. The x12 is very likely overwhelming that engine. Just keep a prop on it and have fun. Sounds like keeping an extra prop on hand may be a good plan as well? I don't know if you can fix your damaged prop cheaper than what you can get a new one for.

 

[NYBo]

You are unlikely to get more than a brisk walking pace out of the motor, regardless of prop. Just not enough ponies. I would look for a bigger motor.

 

[Groo]

The old prop might be fixable, or I could maybe just cut it down to 8.5" diameter for a spare.
A bigger motor would be an option, but it would be even worse with the shallows, unless I went with a jet-drive, but good luck finding one used for a reasonable price. By the time I got a new motor with a jet-drive, I would probably triple or more the worth of the pontoon boat. I think I'll just get a jetski for my speed fix and leave the party barge for low speed and alcohol.

 

[NYBo]

The old prop might be fixable, or I could maybe just cut it down to 8.5" diameter for a spare.
A bigger motor would be an option, but it would be even worse with the shallows, unless I went with a jet-drive, but good luck finding one used for a reasonable price. By the time I got a new motor with a jet-drive, I would probably triple or more the worth of the pontoon boat.

A bigger motor would be the same in the shallows as long as you get the proper length leg and mount it properly, so that's not an issue.

I think I'll just get a jetski for my speed fix and leave the party barge for low speed and alcohol.

Um, just, no. BUI is serious business.

 

[Groo]

a more powerful motor will likely have a larger diameter prop, so that will require it to be deeper. A larger more powerful drive would also be more prone to sucking surface air psudocavitation (whatever it is called) I would think if the tip was the same distance from the surface. So I am guessing I would need to be maybe 6" deeper after it is all said and done for power, and 4" deeper when runner for real shallow. It would definitely make a difference.

Plenty of alcohol can be consumed safely as long as it isn't by the captain.

 

[ahicks]

If nothing else, bigger motors are nearly ALWAYS heavier, making a already bad situation here even worse. Further, a boat equipped with manual height adjustment is simply not going to allow for much more power anyway. Likely not enough to make a significant difference anyway. Last, those little 28's kick butt! They may be only good for a walking pace in a 10mph current, but otherwise, they do a nice job pushing a 'toon this size for cruising purposes - and they just sip fuel!

 

[NYBo]

Bigger motors are usually available with PT&T, alleviating the shallow water problem unless you want to go full speed in very skinny water- not a good idea regardless of motor.

 

[Groo]

Either way; I don't plan on changing out the motor......now if a second one were to hit the used market locally......