Trapper 300 folding prop

[JAYEL]

When I bought my Trapper 300 in 2000, it sported a very flimsy 12/8 knackered folder, the two blades not geared together,and usually in times of crisis i,e, marina manouevering, only one blade would deploy,result, massive vibration The 300 being light was never good on the engine into any kind of sea. I then tried a fixed three blade 12/ 8, which pushed the boat along, but slowed the 300 under sail. From the day I owned the boat, the Yanmar YSE8 has always smoked ,and left a soot trail if I tried to get that extra knot. I now have a GORI 8/13 folder which does the job, but still leaves soot if pushed. The engine on a motor against the wind back up the Thames to Thurrock from Sheerness would drop the oil level from max to min. Is this acceptable for a 20 year old Yanmar? The engine always starts 1st time and idles OK at minimum revs. Am I over propped, or is the engine knackered? This is my 1st yacht, having just graduated up from dinghys Advice please.

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[Stemar]

Since no-one who knows what they're talking about has replied, here's my 2p'th.

Is your engine knackered? Probably a bit, possibly a lot.

Are you overpropped? Most likely.

Oversimplifying what is is a potentially complex situation, if your engine is reaching full revs with the prop, it's not over propped; if your engine's running out of puff before full revs, then you are. Thge black smoke is certainly suggestive of this.

I'm not familiar with the Trapper 300, so I've made several assumptions that may be wide of the mark when working out prop size. My software works on a standard 3 blade prop, but assuming a 22ft waterline length, 2 tons displacement, (these don't make an enormous difference) max shaft rpm of 1500 and 8HP from the engine, it suggests a 10 by 7 prop. Reduce the shaft rpm and the prop size goes up

If these figures are anywhere near right, you were certainly overpropped with the 3-blader, and if the GORI gives the same performance and runs out of puff at about the same revs the same will apply. This is the most likely cause of the black smoke, but there are others

As far as the oil consumption is concerned, an old engine will use more oil than a new one, and will use even more if it's pushed hard. At some point the oil consumption becomes excessive and it's time to do something that will bring great pain to the wallet.

If the oil's going down the exhaust pipe, but the engine's a good starter, it suggests valve guides and oil seals may be the culprits. In that case I'd expect blue smoke. If it's going into the bilges, but there are no obvious leaks at the top of the engine, it could be crankshaft oil seals, possibly indicating tired main bearings. In either case, terminal engine failure is more likely to be due to the oil level dropping off the dipstick than unprovoked, but it's unlikely to be worth just fixing the immediate problem. A complete reconditioning is likely to be more cost effective, though a second hand engine in good nick (but there's the rub...) could be a better bet, especially if it has a bit more power to drive the nice prop you've got. This would certainly improve performance into a chop.

Good luck!



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[JAYEL]

Thanks for that Stemar. The engine shows no blue smoke, nor is there any evidence of any seal failure leakage into the tray below the engine. My quandrary is, bearing in mind the present oil consumption, is it easier on the engine to press on at lower revs/ present prop set up, or higher revs/smaller prop

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[Spyro]

Firstly your YSE8 will be a lot more than 20 years old as they stopped making them in 1978 when Yanmar introduced the YSB8, very similar but with an aluminium gearbox. I have a trapper 300 with the YSB8 which just like yours smokes a lot if pushed at full throttle. Mine will cruise quite happily up to 5.5 knots on a flat windless sea. anything above that it starts to smoke. It uses very little oil though. I have been told by Yanmar engineer that that is normal for that engine and would have done that from new and not to worry about it. I have a two blade fixed prop which will push the boat up to max hull speed but as I said does smoke a bit at that speed. In your case the oil loss does sound serious if you are losing that much that quickly.

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[JAYEL]

Thanks Spyro; What size prop have you got? and how much clearance do you have? P.S. I think its a great name

<hr width=100% size=1><P ID="edit"><FONT SIZE=-1>Edited by JAYEL on 05/12/2004 16:42 (server time).</FONT></P>

 

[Spyro]

Jayel
From what I can remember it's 12X8 or maybe 11x8 it is stamped on the prop but it's still in the water so I can't be sure.
Try posting <A target="_blank" HREF=http://www.voy.com/106963/>HERE</A> for info

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