Prop problem - I hope is all..

[Wile E Coyote]

First, I know this is a rib forum, but a boats a boat, right? Not I know, however, maybe someone can help.... Bought this rig a while ago. First outing, terrible! Took motor into Evinrude agents for major service. Well worth it. Boats a Driver 440 +/- 16'. 70HP Evinrude 3cyl. 2 stroke +/- 1994. Props a 3 blade 13" X 14" pitch. Heres the thing. Over revs at full throttle. Tried a adjustable 4 blade ProPulse 13" x 16-20" prop. At 16" pitch, not enough power for skiing. With the 14" pitch though, still takes ages to get the boat out of the water. I just feel that the performance of the boat should be better. ARE THERE CHEAP NO NAME BRAND PROPS OUT THERE FOR SALE THAT COULD GIVE A POOR PERFORMANCE? Any suggestions welcome PLEASE.

[Nick Hearne]

Hi, any prop will be a compromise, as if you want to water ski you need lower pitch for the grunt to get you out of the water, but you will loose top end speed!
You can get props that adjust there pitch automatically but you are talking a lot of money!
Steel developments would be worth a call for some advise!
Nick

[Pete7]

Hi and welcome, I had an Evinrude 70 on a Ribtec 5.35, so not that a different set up. Engine came with a 13 x 17 prop which turned out to be perfect reaching max revs and a top speed of 36 mph with 2 people. Engine pulled well and would cope with 4 divers and kit.

Any chance you could borrow a standard prop off your dealer to see if it is the prop ?

Pete

[Wile E Coyote]

New to the area here in Lacashire. Ran at Windermere last summer, but they have introduced a 10 MPH speed limit this year. Not too good for skiing. Do,nt know any dealers around. Expensive to buy props for trial and error. Sort of hoping that my idea of the prop I bought the boat with could be "substandard". When I bought the boat this prop seemed "new". Giving me the idea that the seller got a cheapy and put it on for the sale. Having read that the shape of a prop will give more bite etc. Also at top end of throttle, I will reach say 35mph at 5000 RPM and it will stay there whilst the revs climb to 7000 RPM. No change in speed as the revs climb. I'd hate to spend loads of money on say a 13" X 16" SS prop when I maybe need a good 13" X 14" prop in the first place which is what I have on at the moment.

[Alan]

Whilst you will get good advice and welcome here cos Ribsters are a friendly bunch to all, might be worth checking with the hardboat muppets on http://www.boatmadforum.co.uk/ for some further assistance.

[Steel Dev]

Hi there, just noticed this thread about a prop problem. I have checked the OMC parts manual and they do not list a 13" x 14" prop so can only come to the conclusion that it is possibly not this size or it has been altered at some time in its life. If you let me know the part number on the prop I will look it up for you.

As to size for the set up you have with the main use of skiing I would recommend one of the following
3 blade aluminium 13.5" x 15" @ £89.99 + vat
4 blade aluminium 13" x 15" @ £99.00 + vat
3 blade stainless steel 13.3/4" x 15" @ £210.00 + vat
4 blade stainless steel 13.1/4" x 15" @ £299.00 + vat

3 blade Vs 4 blade.....
3 blade higher top end speed. 4 blade give better acceleration and midrange but slightly reduced top end

It might interest you to know that propeller pitch can be altered by 1" up or down. Normal cost for this service £34.50+vat. However if a propeller is purchased from us we will alter it and give a 50% discount off this price, to get the discount you just need to have a copy of your invoice, so hopefully this will take away some of the concerns about propeller sizing.

Hope that helps but if you have any queries please do not hesitate to give us a call 020 8874 7059.

[Searider]

Originally Posted by Wile E Coyote

Also at top end of throttle, I will reach say 35mph at 5000 RPM and it will stay there whilst the revs climb to 7000 RPM. No change in speed as the revs climb. I'd hate to spend loads of money on say a 13" X 16" SS prop when I maybe need a good 13" X 14" prop in the first place which is what I have on at the moment.

35mph (30kts) at 5000rpm is not far wrong.

This sounds like either the prop is cavitating / ventilating at high speed or that the rubber hub is letting go when under load. Either way send your prop off to a specialist for inspection and possible repair or renewal.
Most propeller specialists can turn around a prop in a few days.

Regards

[roofer]

i live in colne and have a 17 pitch stainless prop you can borrow ,pm me if you want to try it .

[Wile E Coyote]

Thanks all so far. Don't know if I've done this right, but if there is a bad pic of my boat, this just gives an idea of size and why I feel with a 70HP I should be getting a little more.

[Wile E Coyote]

Motors +/- 1984, not 94.............