What Prop?

[Phil Bennett]

Hi Fishraiders,

I just recently put a new 90 V-Tec Honda on my 16 ft Haines Hunter . All is well, plenty of power with amazing fuel eccon, but feel I'm laking a little top speed. With a 13" by 17 pitch alloy prop I'm getting 41 mph (or 67 kays) WOT. It was over reving (6200 rpm) so I tried 13" by 19 pitch alloy prop. GPS readings tell me nothing has changed, same grunt, same top speed, though I noticed a little cavitation...

Not sure what to try next. Whilst I'm no speed freak, I thought I'd be able to reach close to 50 mph mark (As I've read reviews on bigger, heavier boats getting close to these speeds) Whilst blistering top speed would be fun, I'm more hoping to gain higher cruising speeds in the 3500 to 4000 rpm bracket to eat up the miles on our big northern rivers.

As it stands 3500 rpm is 23 mph (37 kph). And 4000 rpm is 26 mph (41 kph). The boat is 4.8 meters by 1.93 wide and only weights 350 kg.

Any suggestions??

Cheers

Phil

[IWANNABROCK]

If your prop is cavatating, you are pushing air not water, maybe drop motor down a bit.

[a boat]

Good Morning Phil, I am not sure why going from a 17 inch to 19 inch is going to cause cavitation if nothing else was changed. Was the outboard cavitiating with the 17 inch?

Also I am surprised that the engine does not come with a SST prop. I would be asking the selling dealer to supply you with a 19 inch SST prop and your revs should drop down below the max WOT RPM recommended by Honda and your speed will increase compared to the alloy. I have the Honda price list and the price you probably paid for the outboard it should of came with a SST prop and that is what I would be wanting if it was my outboard.

Try a 19 inch SST and see what happens,

Cheers,

Huey.

[Phil Bennett]

Good Morning Phil, I am not sure why going from a 17 inch to 19 inch is going to cause cavitation if nothing else was changed. Was the outboard cavitiating with the 17 inch?

Also I am surprised that the engine does not come with a SST prop. I would be asking the selling dealer to supply you with a 19 inch SST prop and your revs should drop down below the max WOT RPM recommended by Honda and your speed will increase compared to the alloy. I have the Honda price list and the price you probably paid for the outboard it should of came with a SST prop and that is what I would be wanting if it was my outboard.

Try a 19 inch SST and see what happens,

Cheers,

Huey.

Hi Huey,

I choose the alloy prop to save a few bucks, though in hindsight I perhaps should have picked the SS model...

Iwannajewy, I think part of the cavitation problem was me triming the motor a tad high and turning a bit hard. I've used the boat 3 times since, trimmed in more and not pushing so hard through the turns. So far no cavitation.

Huey, do you think there's a great deal of difference, preformance wise, from alloy to SS? Or more specifically, what sort of top speed gain is liable to be made by an SS prop of the same pitch? Just trying to weight up whether you spend the extra and get an SS model. If the gain is minimal I'll stckl with the alloy.

Thanks

Phil

[a boat]

Hi Phil, a SST prop of the same pitch as an alloy prop will perform better due to cupping, thinner blades and ability to run the engine at a higher setting and therefore having less drag in the water. As mentioned I am surprised Honda do not just supply SST props with their engines, because at new the cost differnece would only be about $350 and well worth it in my opinion, but now to buy a SST prop might cost you more from your dealer, unless he wants to do the right thing by you?

As mentioned I think the best prop for your rig would be a 19 inch SST, your revs would be ideal and give you the best mix of acceration and top speed.

Cheers,

Huey.

[Phil Bennett]

Hi Phil, a SST prop of the same pitch as an alloy prop will perform better due to cupping, thinner blades and ability to run the engine at a higher setting and therefore having less drag in the water. As mentioned I am surprised Honda do not just supply SST props with their engines, because at new the cost differnece would only be about $350 and well worth it in my opinion, but now to buy a SST prop might cost you more from your dealer, unless he wants to do the right thing by you?

As mentioned I think the best prop for your rig would be a 19 inch SST, your revs would be ideal and give you the best mix of acceration and top speed.

Cheers,

Huey.

Thanks for the info, Huey.

I'll look into a SS prop in the same 19 " pitch. Might be able to sort out a deal with the dealer I purchased the motor from. As it stands I'm happy with the boats preformance, I just thought I may be lacking a little top speed compared to others I've spoken to. THe SS prop sounds like it may be the answer.

Cheers

Phil