What prop?

[Leaderscharter]

Hi guys,
Really appreciate any input you fellas might have to this situation.
I have upgraded from a 2 stroke 150 to a f150 on my 7m crompton. Currently running the original 3blade ss 13.75 dia. x 19 pitch from my last engine. This produces 35 knots gps at 5200 rpm with a light load.
The boat is operated comercially and coded for eight so it is more important to be able to cruise with economy that outright speed. I have it on good authority that for best economy with this motor you should prop it to run as close to max rpm as possible.
I was thinking 13.75 x 17 in 3 blade ss. ?
Any ideas or suggestions appreciated.
Cheers Aaron.

[martini]

According to Yamaha, the F150 max rpm is 5000-6000 which is a bit vague.

If you went down to a 17" you should make 5400-5500 under your light load conditions.

But with 8+1 on board you should find the motor will still be really struggling, a 15" will be much better.

Also, not true re propping for max rpm to get best economy. I had 19" on my boat which gave correct max rpm. I changed to 17" and although I could over rev the motors at WOT under most conditions, at a given cruising speed I was burning less fuel even though the revs were higher than with the 19". Less load on the motors.

Your boat is well under powered with 150hp, when the yammy goes bang stick at least 225 on there

[Erin]

Originally Posted by martini

when the yammy goes bang stick at least 225 on there

Just not an Opti though

[martini]

Originally Posted by Erin

Just not an Opti though

Absolutely

[Pikey Dave]

Cue Gotchi, the caped etec crusader!

ee lad, tha can't educate pork

[Hightower]

15" pitch sounds good to me, When you're fully loaded you'll really struggle with the 19"er. How about getting two props, a 15" and a 17"er. Just swap em over to get the max out the set-up depending on loading/sea conditions? The one you don't run will make a terriffic spare.

[Hightower]

BTW aren't Mercury, Yam, Honda 15 spline props interchangable?

[Leaderscharter]

Thanks guys.
Martini I would love a 225 but to tell you the truth for our needs the 150 is ample.
I had an option of an optimax but in this neck of the woods yamaha is the only way to go. I will look at getting hold of a 15 so. Almost swallowed my tongue earlier when I was quoted €550 +Vat for a black yamaha stainless 13.75 X 17.

[martini]

Mercury have the best range of props, you just need the correct flo-torq hub. Lots on ebay USA, mirage plus if you want 3 blade or revolution 4 if you want 4 blades (you'll need a 13" Rev4 though, not sure if they go down that small)

[Leaderscharter]

Ok have ordered a 14.5 X 15 3 Blade SS from the US fingers crossed it does the job.
The extra diameter will mitigate the reduction in pitch I'm sure but it is impossible to know for sure until I get it in the water
Will post the results.

[Pikey Dave]

I'm assuming that the gearbox will accomodate the extra diameter without catching?

[Leaderscharter]

Originally Posted by Pikey Dave

I'm assuming that the gearbox will accomodate the extra diameter without catching?

Diameter should not be issue as some are running 15.25 on f150's

[Pikey Dave]

[dun_buyin]

Originally Posted by Leaderscharter

Ok have ordered a 14.5 X 15 3 Blade SS from the US fingers crossed it does the job.
The extra diameter will mitigate the reduction in pitch I'm sure but it is impossible to know for sure until I get it in the water
Will post the results.

Did you order from fleabay or go direct to a US supplier? I'm thinking of ordering a new prop from the States but would rather deal directly with a store. Anyone else got any recommendations, or are there any UK based stores that are worth trying?

[Pikey Dave]

I bought my props from the dealer that supplies all my other bits & pieces. Probably not the cheapest deal that I could have got, but he supplied them on a try & buy basis. I.e. if I didn't like them, he would take them back & swap them for a different model / pitch, as long as they weren't damaged. You won't get that service on Fleabay.
Sometimes, cheap ain't cheap

[Hightower]

Originally Posted by Pikey Dave

I bought my props from the dealer that supplies all my other bits & pieces. Probably not the cheapest deal that I could have got, but he supplied them on a try & buy basis. I.e. if I didn't like them, he would take them back & swap them for a different model / pitch, as long as they weren't damaged. You won't get that service on Fleabay.
Sometimes, cheap ain't cheap

There's no point in telling us all this and then keeping the dealers name stoom

[Pikey Dave]

Originally Posted by Hightower

There's no point in telling us all this and then keeping the dealers name stoom

Mike Vincent at South Coast Marine in Christchurch. Top bloke

[Leaderscharter]

I thought I had it ordered from Overtons, paid online for a prop on sale at a very good price. Unfortunately there was some mix up when processing the order and someone else bought it in the meantime. As it turns out a price from a local supplier was not too much more so I decided to go with the easier option, should be in by Tuesday.

[dun_buyin]

Not bad if you can get it locally for not a lot more outlay and I'd be happy to do that myself. I've been quoted almost double the cost of ordering from the US. I could get a Mercury Vengeance 21" pitch stainless steel prop for about £400 (including delivery) by ordering from the Mercury US website. Locally (here in Australia), the list price is closer to £800. Most places would have to order in as well so it's not as if I can try out different ones. Currently looking to see if there is a cheaper deal out there. Had a look at Overtons but they don't appear to stock Mercury/Quicksilver.

[GordyP]

I replaced the Viper props I was running with Apollo props which were nearly half the price, I have been really impressed by the grip provided by them. Went for them as the local Seafari guys use them.