What prop?

[Leave Blank]

I purchased a pontoon last year that I stuck a 50hp on. Man that thing was SLOW!.

So I recently got a 1979 Mercury 80hp that had a 21 degree prop on it that I had to cut off. Man that thing was stuck! Even took it too a local marine shop that charged me 90 dollars and had it for 5 days to tell me...we can get it off.

So anyways, I need to order a prop.
The pontoon is a 25ft crest with an 80hp merc and will be loaded down with 2 stand up jet skis/gas and several peeps.

Any recommedations?

Thanks

 

[Old Screwball]

Re: What prop?

I can only tell you my experience. I sold a 75mph go fast boat for our toon. Just not enough room in the go fast for grand kids and all their 'stuff'. We bought an 18' Sun Tracker Party Barge. I optioned the biggest engine the transom rating would allow, a 75hp Merc 4 stroke. It came with an aluminum 13 pitch, I had a 15 stainless and a 17 aluminum. Wide Open Throttle on that motor is 6000 rpm. With the 15 and 17 pitch the best I could do was 4600rpm and 18mph (gps) With the 13 pitch I topped out at 24mph and 5600rpm. That is with 4 adults, food and drink for a days cruising. Pretty nearly any prop seller on the web has a size calculator. Prop pitch depends on the size of the boat, engine RPM and load. With that 80hp and 25' of boat, I doubt you will get any more than 20mph..... if that.

Good Luck

 

[MH Hawker]

Re: What prop?

Common pitch props for a pontoon is 9, 11, 13 , 15, ever thing is depended on boat type pontoon size and motor., I would suggest a 11 but with out knowing a good bit more it really is a put guess.

 

[Leave Blank]

Re: What prop?

11 it is. I just didnt want to play the prop game. If I get 15mph loaded I will be happy.

You should have seen how bad the 50 tried to push the pontoon with a load. I gps,ed me only and it was a respectable 17. Loaded it was 8/9 and sounded like it was going to come apart. The tray where the motor mounts was plowing water.

This is my first toon and I really like the ride. I fixed up a little open bow citation a few years back that was okay but with the room and ride of the toon,the speed doesnt bother me. I just want to be able to get out of peoples way and if a storm is coming make it back safely.

Thanks for the help!

Oh and sorry for the lack of info. I just dont know anything about this motor. I have yet to mount it. I just finished maintenance. I looked for hours trying to find a prop calc but didnt find any recommendations for the boat. Just the different degrees.

 

[MH Hawker]

Re: What prop?

Well you really need to know the motor WOT rpm, thats the big thing, pontoons dont have the speed because of the hull type. With out some rpm and prop pitch to start off with you wont know what to use.

I hope some one with a 80 hp 2 stroke and a 25 foot boat will chime in to give you a lot better idea than my pure guess.

A lot of people around here do what you have in mind Its the filling station and floating grill. It works real good.

 

[Leave Blank]

Re: What prop?

Well I am sure the 11 is fine. Just ordered the 14x11 from this site.

 

[lncoop]

Re: What prop?

Well I am sure the 11 is fine. Just ordered the 14x11 from this site.

Just keep in mind if it's not fine you're stuck with it. No returns on props that have gotten wet. If you're okay with that go nuts. Welcome aboard.

 

[Silvertip]

Re: What prop?

Pontoons need a "pontoon-specific" prop. They, like work boats, need the push of a large, elephant ear prop in either three or four blade configuration. Check your suppliers. Pontoon props also work better in reverse since they have larger blades.

 

[WaterDR]

Re: What prop?

I try to always get props local that have return policies.

It really is a get things close, then trial and error sort of thing.

What ever you do,I would try to pick the right style and stick with it. That way, you only need to change pitch to get it dialed-in.

 

[Leave Blank]

Re: What prop?

I dont have anyone local to swap props with.

Is the 14x11 a bad place to start? I guess we wont really know until we try it and see what the rpms are. I still need to water test it with muffs and then go to the lake and mount it. Thats why I was hoping to get really close on the first try.

 

[MH Hawker]

Re: What prop?

I think it will be close.

 

[WaterDR]

Re: What prop?

I dont have anyone local to swap props with.

Is the 14x11 a bad place to start? I guess we wont really know until we try it and see what the rpms are. I still need to water test it with muffs and then go to the lake and mount it. Thats why I was hoping to get really close on the first try.

Any local prop show will allow you to try props. Frankly, I think the 11 will likely be the one. It won't be a 9, so it will either be an 11 or a 13. I run a 15 on my rig with a 115.

 

[craigmack]

Re: What prop?

Even if the 11 is wrong you're not "stuck" with it. You can always sell it, but honestly, I would keep it as a spare (it's cheap insurance). It's always a good idea to have one aboard for that rare time you lose one! Don't forget a spare nut, washer and cotter pin as a spare prop is useless without them.

 

[Leave Blank]

Re: What prop?

Awesome guys! Makes me feel alot better.
Cant wait to try the new motor.

This project has been a handfull for sure with a stuck prop and a bad wiring harness,but it is finally coming to an end!

 

[lncoop]

Re: What prop?

Awesome guys! Makes me feel alot better.
Cant wait to try the new motor.

This project has been a handfull for sure with a stuck prop and a bad wiring harness,but it is finally coming to an end!

Yeah, I agree eleven is a good place to start. Didn't mean to scare you away from that pitch. I just wanted to be sure you understood you wouldn't be able to return it to iboats.

 

[KrisKastel]

Re: What prop?

I like a pontoon boat with a higer pitched prop for more acceleration, rather then top speed

 

[Jeep Man]

Re: What prop?

You should be good with the 11p. I had an 11p on my 60 bigfoot and it was right for rpms. Had some damage so I switched to a 9p backup and was over reving a little. A note though, I switched to a 4 blade 11p and found I was under optimum rpms. When going to a 4 blade you need to drop down by 1. Will be swapping out for a 4 blade 10p before launch time in the spring.

 

[Bamaman1]

Re: What prop?

You'd be looking at a 11 pitch or 13 pitch. It's a shame there's no propeller shop around to give you free advice with a purchase. They'll often let you take numerous props out to test, too. I'd say go with the 11 to start.

If you're somehow carrying a couple of JetSkis on your boat, be careful. If you put a bunch of weight on the front end a pontoon, the rear end lifts. That often causes the propellers to ventilate--acts like the prop dropped off.

Like was said, if an 11 overrevs your motor, you can keep it for a spare. Aluminum props online are just over $100, and they're readily available on EBayMotors.com and Craigslist.com for far less.

 

[Leave Blank]

Re: What prop?

Thanks for the advice. Got the prop yesterday and went to put on the newprop to find my splines are twisted a bit.
May have been why I had to cut the prop off.
There was no dings on the old SS prop. It WAS mint,now not so much haha. The new prop spines do not go all of the way back like the other so I will try making sure the splines are clean and free of burrs. Also check it to see if it is bent.

If it is bent then I will have to find another lower unit. This one is on its last leg. It must have sat in salt for a while because it is bittle and pitted. Was at least. Its all cleaned /filled and painted now.

My cheap craigs list find isnt cheap anymore.

 

[steelespike]

Re: What prop?

From your loaded performance description I kind of wonder if any motor will get much more for you.
With a light load maybe you would make 20. 10 or 11 maybe with all that dragging through the water.
Let us know how you make out.
Be sure you put some grease on the shaft when you install the prop.