Propellers

[muchy_]

I need to change my prop to a larger pitched one due to having a more powerful engine put in. Looking at props there are turbine props and equipoise props. Can anyone explain what the difference is between these two types and what the pros and cons are of each......

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[Bejasus]

Hi Muchy, I am about to do the same, and the propellor is coming from Stalham. You have a displacement hull so the best prop for you is a turbine prop. Equipoise props are designed for semi-planing hulls. Do know what size you are switching to?

You can find out a bit more <A target="_blank" HREF=http://www.vetus.nl/producten/product_main_98_2.asp>here.</A>


The P3B is turbine and the PC3B is equipoise.

Actually, just checked and the Seamaster 30 had a claimed top speed of 13 knots, but I imagine that that was with the twin Perkins fitted. Although it would suggest a semi-planing hull, so not sure if your single 1.6 XLD would get the boat up there.
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[muchy_]

Hi George, thanks for the reply. I have also seen this claimed hull speed for the Seamaster 30 but I'm not really trying to get it up to that. I'm trying to make 9 knots which should be ok with the XLD 416.
I think I need a 10" pitch prop to get to that speed and I think (not sure) that the boat has something like a 7" on at the moment.
How are you finding the 418?
You say your prop is coming from Stalham, I wasn't aware of a chandlers in Stalham where abouts? Maybe I'll give a look see.
I'll look out for you when I'm down south on me hols

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[Bejasus]

Not a chandlers, Mike. Local company that supplies most of the hire co's & fishing boats. (Name escapes me.) Anyway for a 12 x 10 = 120 + vat. Vetus wanted £106 but it came with a standard 25mm shaft size wich they then charge £86 to have machined to 1 inch and then add VAT. The local co. to you, had one on the shelf with the correct pitch and taper.
New 1.8 isn't in yet, but new bearers are fitted and some other jobs done. Need to paint, rewire & otherstuff when I get home next week. Also pick up & fit new prop.

Whats the biggest prop you can fit? I worked it out roughly for you, and for 9 mph, a 14 x 9 would do the trick, but if you give your HP, max rpm & gearbox ratio, I can get it closer.


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[muchy_]

Hello again George. Max RPM is 3500. Max HP is 54. I have no idea what prop is on there at the moment but I'm pretty sure I've got the room for a 14" dia if I remember rightly but I've only had the boat out the water for 10 mins and didn't really take much notice of that.
No idea what taper I've got either.......something tells me this aint gonna be as easier job as I thought it was gonna be.....doh!

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[Bejasus]

Ok, i've guestimated the gearbox ratio at 2:1 and an lwl at 28ft. an all up weight of 9000lbs(factory quote 8000) and come up with 9.3 kts(10.7mph) using a 16 x 11 prop. Not a big job once the boats out. Mic the shaft & measure the taper, buy prop & refit. Provided there's room of course./forums/images/icons/wink.gif

Then again, when I run the same figures through another program, it comes up with a max hull speed of 8 knots./forums/images/icons/crazy.gif
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[Althorne]

Hi Muchy,
Missed your mail on it's day as I was trying to get rid of \ Trojan Horse.
For me by far the best people I know for pros' are T.Norris. Isleworth.
Tel 0208 560 3453 and on the net'. Specialise in making props', shafts and the like and drilled my new prop' to suit me at no extra cost. Mine was a 17"x12.5" at £106 so not bad.
Roy

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