Ribcraft 4.8 Yam 90 2stroke prop

[rockyrib]

Hi
I was wondering if anyone might be able to help me.

I recently bought a stunning ribcraft 4.8, it came with an etec 75 (which I had to sell sadly)

I have put my 2000ish yam 90 2 stroke outboard on it.

I was wondering if anyone had a good idea of what prop should be on it, at the moment I have a very chewed up ally one and looking to replace with a stainless one as a christmas present to myself.

Many thanks

Tim

[Downhilldai]

Yam 90 on a Ribcraft 4.8?

[gibbo500]

Originally Posted by rockyrib

Hi
I was wondering if anyone might be able to help me.

I recently bought a stunning ribcraft 4.8, it came with an etec 75 (which I had to sell sadly)

I have put my 2000ish yam 90 2 stroke outboard on it.

I was wondering if anyone had a good idea of what prop should be on it, at the moment I have a very chewed up ally one and looking to replace with a stainless one as a christmas present to myself.

Many thanks

Tim

Chrikey a 90 on a 4.8?????

[gibbo500]

Originally Posted by Downhilldai

Yam 90 on a Ribcraft 4.8?

You beat me to it.

[rockyrib]

Hmm
Yep its rather tasty, I got 42mph on the gps with a wrecked prop (its a trade up from my avon 3.45 with a yam 40)

[matt h]

, blimey, well, over the power rating ..anyway as the engine weighs only 120 kg which is well under the Max weight , try a 13 x 19 ally lets see some pics of her

[outboardtech]

rockyrib if I were you I put put a higher pitch prop on that set up . you dont want too over rev that outboard man and blow the powerhead up . I have seen a 5metre with the same engine and the guy was running a 17 and was reving @ 5800 on W.O.T and the poor powerhead lasted 6 hours . he the customer was so happy as he was getting those revs but didnt really know what he was about to come across . YES a piston thru the block . So my advice and experience would be higher pitch too drop the revs . baz

[Jacob555]

My Novamarine 4.5 metre runs a Yamaha 60 2 stroke. I was reaching a screaming 5900 at WOT on a 15 inch prop so quickly upgraded prop to a 21 inch and its perfect now, topping out at 4950 at 5mph faster. This is a very light boat though. 190kgs ex engine! People with larger ribs think I am very odd running a 21 inch prop with only 60 hp, but its a great setup.

The place I got my prop from on ebay had another Yamaha 23 incher. In fact they have been relisting it for months. The number of customers who need to run a prop of such big pitch on an engine so small (15 spline 4.25 inch gearcase) is probably limited. The item is at http://cgi.ebay.co.uk/propellor-prop...item2ea68336df

I'm not garanteeing it will be right but its easier to work down pitches than up as there's less risk of blowing the powerhead up.

[rockyrib]

Hi Guys,
Thanks for all the help, I have decided to buy an ally prop first just to give it a go and see wether the one I buy is right before going for the stainless baby.

I have bought the one on ebay - £60 seemed dead cheap and I had a few quid in my paypal balance.

This may sound really stupid but can anyone just point out what the numbers mean I guess the pitch is the angle of the blades and the other measurement is the diameter?

So the one I got : 12 5/8 x 23
I guess the 12 5/8's is the pitch and the 23 the size of the blades?

Sorry for sound stupid

Tim

[chewy]

Originally Posted by rockyrib

Hi Guys,
Thanks for all the help, I have decided to buy an ally prop first just to give it a go and see wether the one I buy is right before going for the stainless baby.

I have bought the one on ebay - £60 seemed dead cheap and I had a few quid in my paypal balance.

This may sound really stupid but can anyone just point out what the numbers mean I guess the pitch is the angle of the blades and the other measurement is the diameter?

So the one I got : 12 5/8 x 23
I guess the 12 5/8's is the pitch and the 23 the size of the blades?

Sorry for sound stupid

Tim

12 5/8" will be the diameter and 23" the pitch, ie how much one revolution of the prop will move you forward in the water without any slip.