Prop recommendation for old Harris inboard

[SlowFloter]

Well, I've scoured the net looking for info that will help me make a prop decision for my pontoon, but I'm coming up blank. Here's what I've got:

1992 24' Harris Flotebote
Yamaha 3.0 inboard 130hp
Yamaha sterndrive
Weight - about 2,200 lbs
Current prop - 16" x 14P
Current WOT - 4,400 RPM
Current top speed - 22 mph (GPS verified)

The WOT and top speed are with 4 adults and 4 children on board. It performs fairly well with this prop, great holeshot, seems to grip water well, no obvious slipping or overrevving. I just want a little extra speed, maybe 3 to 5 mph, for skiing and tubing. I think the boat is capable of that given how well it comes out of the hole now, but would love some advice from those who have gone down this path.

All of the prop recommendation tools that I've found online are telling me something more in the 14.5" diameter range, give or take, and anywhere from 15 to 19 pitch. I'm kind of at a loss due to data overload at the moment, so practical advice is what I'm looking for. Thanks!

 

[steelespike]

Re: Prop recommendation for old Harris inboard

Welcome,
I'm unable to find any info on the Yamaha I/O
Do you know the rated wot rpm? Do you have the gear ratio?
It may be on the outdrive.
Seems like a 130 would be faster.
Don't worry about the diameter though on a pontoon usually a larger diameter is best.
Try to find a pontoon specific prop. Usually among the lower pitched props.
Increasing a pontoons speed is a tough assignment.
It would help a little too have the wot rpm and gps speed with just a driver aboard.

 

[SlowFloter]

Re: Prop recommendation for old Harris inboard

Thanks for the welcome and reply. I'm like you, I just thought a 130 would be faster. I saw somewhere that the rated WOT range is 4200 - 4600, so i'm currently right in the middle of the range with a medium load. I don't have the gear ratio, but will hunt around the outdrive for it this weekend. I also should have an opportunity to test the WOT and top speed with just me aboard this weekend as well, so I'll report back.

Also, I just bought the boat and the PO left the boat in the water, so the toons are pretty dirty. How much speed can that knock off?

 

[steelespike]

Re: Prop recommendation for old Harris inboard

I found some info 1.97 gear ratio, Ran it through the calculator and except for the speed it isn't too bad.
24% slip in the ball park for a pontoon.
Dirty tubes could slow you down maybe a couple of mph if dirty enough.
Olso if the prop or outdrive are fouled. What diameter are the tubes?
I imagine with an I/O it probably sits pretty low at rest some pics would be good.
Does the boat seem to lean more to one side? Have you tried to distribute the weight for best
speed? what is the capacity of the boat?

 

[SlowFloter]

Re: Prop recommendation for old Harris inboard

I think they are 25" tubes. And it definitely does sit lower in the back. Whether it's too low or not, I'm not sure, so I'll get pics this weekend. Doesn't lean to one side very bad, however I have asked people to move side to side a couple of times to fix it. As far as front to rear, people have been biased toward the front, but the prop is still in the water good with no noticable slipping or spinning out. The stated capacity is 14 people or 1,980 lbs.

Really appreciate your help! What is this calculator you speak of? Some kind of online calculator or your own pocket calculator?

 

[steelespike]

Re: Prop recommendation for old Harris inboard

No its just a prop calculator on line. i just searched "prop calculator" on google.Clicked on a couple of results. The one I use
is a green page. I think Poson Enterprises.