Getting my prop adjusted

[Jools_of_Top_Cat]

I need to get a standard 3 blade prop adjusted, i.e. an increase in pitch. It is around 15" but I do not know currently what pitch it is set to, there is nothing stamped onto the prop and it was inherited with the boat.

Does any one know who in the North West incl Wales could do this for me?
What should I expect to pay?
How do they alter it, does any one know?
I have been told of a place in Caernarfon (Castle Marine?) Any one know where they are? I have thought about Alec Martin in Birkenhead, but he only seems to open similar hours to banks so a bit restrictive as I would have to travel to him.

Thanks in advance

<hr width=100% size=1>Julian

<A target="_blank" HREF=http://www.topcatsail.co.uk/Honda_00.html>Honda Formula 4-Stroke racing</A>

 

[Stemar]

Re: Castle Marine

www.castlemarine.co.uk

Castle Boat Yard, The Harbour, Caernarfon, Wales
01286 674322



<hr width=100% size=1><P ID="edit"><FONT SIZE=-1>Edited by Stemar on 10/09/2003 21:37 (server time).</FONT></P>

 

[Jools_of_Top_Cat]

Re: Castle Marine

ok, having looked at their site, very good thank you, and yanmar I have a question for yanmar 1GM10 owners, what rpm do you cruise at, this makes a big difference to the prop size and pitch, so while I go about altering my prop(s) I would like an idea of an ideal running speed?

any offers?

<hr width=100% size=1>Julian

<A target="_blank" HREF=http://www.topcatsail.co.uk/Honda_00.html>Honda Formula 4-Stroke racing</A>

 

[steve28]

prop sizes vs. rpm

if you tell me what gearbox and boat lenght at water line i can tell you what prop size you need
you should get 3600 @ the crankshaft when in gear @ full throttle with no tidal or weather influences


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[Guest]

Re: prop sizes vs. rpm

Don't you mean when OUT of gear.

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[dickh]

Re: prop sizes vs. rpm

I thought the ideal is that at max loading ie in gear & full throttle, the rpm should a little below the max permissible full load revs. I'm not familiar with the 1GM but assume it is 3500 at theoretical max load, so actual full load speed should be about 3200/3300 rpm.
My perkins will rev to 3500 under no load and under full load at the beginning of the season with a clean prop, I get 3200/3300 which I'm quite happy with.

<hr width=100% size=1>dickh
I'd rather be sailing... /forums/images/icons/smile.gif

 

[steve28]

Re: prop sizes vs. rpm

yes i do mean out of gear, for a 23 foot waterline and a 1gm10 not a 1gm which has a max rpm of 3400
this is the advisabe props and gearbox ratios

2.21:1 11x7 rh
2.62:1 13x8 rh
3.22:1 15x9 rh which is the one i use

i get 3602 rpm out of gear using a shaft tacho
in gear i get 3590 under most conditions

steve

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[Jools_of_Top_Cat]

Re: prop sizes vs. rpm

Thank you for that, I tend to try to cruise at 2100 rpm alt sensed, now this would mean shaft revs of approx 950. or is this arse about face.

Are you suggesting that you run your engine at over 3000 rpm, this seems a little fast to me, maybe I am not running them hard enough. 2100 seems quite quick to me, but I have in the past been used to bigger lumps, which will cruise at 1200 rpm.

have I got this wrong, if I have the engines cruising too slowly then both my props are way out, oh dear the bills are building again over winter.

<hr width=100% size=1>Julian

<A target="_blank" HREF=http://www.topcatsail.co.uk/Honda_00.html>Honda Formula 4-Stroke racing</A>

 

[steve28]

Re: prop sizes vs. rpm

if they are 1gm10 engines then they are designed to run at the max rpm speed so the prop is set to obtain this rpm. if it isnt it will load the engine up to much and produce abnormal load which in turn produces black smoke.
it may be worth a call to french marine 01206 302133
they are yanmar agents and also produce and repair props so they can advise you accordingly

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[John7]

Re: prop sizes vs. rpm

Yanmar say the GM series (1M10 etc) can be run for up to one hr at 3600 and 3400 is the maximum cruising engin speed. The usual speed for best economy and engine wear etc is 85% so about 2.8/900 (the yammer tachometer reportedly under reads revs).

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