Upgrade propeller on 40hp?

spartacus · 04 March 2008, 23:59

Has anyone upgraded their propeller on a Yamaha 40hp? I know it's a relatively small engine, and costs may be prohibitive - but would welcome views on the subject.

Engine is a mint 1995, Yamaha 3 cylinder, 2-stroke, Autolube, long-shaft, manual start, trim and tilt. (model 40v).

It has a standard aluminium propeller 12 1/4 diameter x 9 pitch (G) and WOT is 5,500 rpm. I gather I may increase speed by an extra 2-3mph with a new propeller. Not sure if Yamaha do a polished stainless steel one, or maybe Solas, but I suspect they probably do.

nexus · 01 March 2009, 02:01

Anyone ever have an answer for this? I have an F40 I need a prop for. The stock one has seen better days. Figure now is the time to change it up if I'll ever do it.

Pushing a 14' SIB.

reinier · 01 March 2009, 12:34

That's no problem, there are many props for the Yam 40hp 2-stroke and 4-stroke. SST and Aluminium... You might want to go with a 10" SST, expect to get 1 or maybe 2 mph out of that, but you'll drop in acceleration speed! Something to consider. Btw, 9" pitch is very small... You're getting something around 22-23 mph now I think. Upgrading to another prop can be very usefull or even necessary, but with this sort of speeds and this horsepower it's not worth the money at all.

5500rpm is the max for your engine, so this is not the wrong prop.

PeterM · 01 March 2009, 13:39

I considered this on my Yam 50 ( 4s) , but general advice I had was its not worth the money - especially not for a SS one. Maybe to change the pitch if it wasn't in the right rev range, but unless you are are serious speed merchant its not worth it . If you want more speed get a bigger engine I was told .........

I'd be interested to hear what the outcome was if you did go for it.

spartacus · 03 March 2009, 13:20

Quote:

I'd be interested to hear what the outcome was if you did go for it.

Never did get around to the upgrade. The Yamaha S/S prop is prohibitively expensive. They never come up on the second-hand market and tend to stick with the engine they were purchased with.

I did look at upgrading the engine too - but the 3 cylinder carbs from a Yamaha 50hp are like hen's teeth, plus apparently I'd need the exhaust manifold.

All in all - would be easier to simply upgrade to a 4-stroke 50hp, or find a mint 2-stroke Yamaha 50hp.

samt · 03 March 2009, 14:46

Quote:

Originally Posted by spartacus

Has anyone upgraded their propeller on a Yamaha 40hp? I know it's a relatively small engine, and costs may be prohibitive - but would welcome views on the subject.

Engine is a mint 1995, Yamaha 3 cylinder, 2-stroke, Autolube, long-shaft, manual start, trim and tilt. (model 40v).

It has a standard aluminium propeller 12 1/4 diameter x 9 pitch (G) and WOT is 5,500 rpm. I gather I may increase speed by an extra 2-3mph with a new propeller. Not sure if Yamaha do a polished stainless steel one, or maybe Solas, but I suspect they probably do.

My old 40hp mariner came with a similar prop to yours, they are a large diameter and are really made for pushing heavy loads. I think mine topped out at 27mph with that prop. Acceleration was awesome though

I upgraded to a 15 pitch prop, with a 10 1/4 diameter. This raised my top speed upto 38mph. Lost abit of acceleration but nothing noticable. This was a standard blackmax prop, pretty sure it was alluminum. Cost around 100quid. My rib was quite light, and I maybe could have gone for a 17, which should have pushed it over 40mph.

nexus · 07 August 2009, 06:29

Never did wind up changing the prop. The cost for SS prohibitive for a gamble on marginal improvements. What I want is more top end speed which a different prop would definitely give, however the problem is that my boat becomes a little unstable at higher speeds when running over mixed swell and wind chop. It has a tendency to shimmy a bit. This is a direct result of it being tiller steer. I have no interest in cluttering the deck with more junk like a steering console so upgrading a prop for more speed would be wasted on my setup. If I had easy access to a lake or river I would likely have made the change but when it comes down to it, I'm a boater of convenience and what is convenient for me is the ocean 2minutes from my house.