Propping up the bar

[Guest]

I would like some advice on improving the set up of my Inboard/Outboard arrangement.
I have a Ford 416 XLD 1600cc diesel, with an Enfield (model?) outdrive, all squashed into a Fantasy 20(possibly?- Very little information was available when I bought the boat)
Now its a pussy cat on the canals and will trawl along at 3-4 knots at little more than tickover creating little more than a ripple. However, I spend most of my time on the Severn and the RPM required seems disproportionate to the progress made. The engine does not sound like its actually doing much work.
Is it under propped? 60 ish HP engine and 20' boat would seem to be a fairly swift combination on paper. When you open it up it doesn't produce a great deal of wake, so the hull seems appropriately shaped for moderate speed.
Its currently running a 12.5" x 13 pitch well battered(BCN canals for you!) ali prop. I guess the top speed is 15 knots - speedo is not working - another winter time job!

I would really appreciate any guidance not on improving top speed, but reducing RPM at comfortable cruising speeds mainly to reduce the noise. As I said the prop is decidely 2nd hand after 10 days on the canals this year so its due to for change. I'm not sure I could physically fit anything larger diameter onto the Enfield.
I would also like any information about the Fantasy 20 (where and when was it built) and the Enfield outdrives (maintenance schedules/requirements, is the propellor compatible with other makes, whats the largest prop that may be used etc) that anyone may have.

I know its a big ask, but thanks in advance for ANY info that you may have.
Jason.

 

[Geoffs]

Hi Jason,

I was waiting for some one with a bit of knowledge on props to respond, I'm no expert, but rather than ignore you here goes.

Lots of things to think about here. Firstly, 15knots, that's nearly 18 mph - getting rid of knotty things, doesn't sound too bad for 60hp in 20ft (especially for the BCN!). Next a battered prop will have a significant effect on the top end performance of your outfit. I've seen really mangled props that do quite well at medium revs, but no good at all flat out.

I've played around with props on my boat, 20ft, but I've got 145hp. (not used in inland waterways!). If you touch bottom, or anything else, an ali prop will lose pitch. I've just touched sand, with no apparent damage, other than a bit of paint gone, but definately lost pitch. When new, wide open throttle pulled 4000 rpm and gave 38 mph. After a year of misuse, 3/4 throttle gave 4,500 rpm and 35 mph.

So Iwould say have your ali prop reworked, about £30, you can even asked for the pitch to be altered +/- 1 inch. Keep the ali prop for the BCN, treat yourself to a stainless prop for cleaner waterways. A S/S prop will keep it's pitch better, though probably won't survive a shopping trolley unscathed.

I've found Steel Developments (020 8874 7059) very helpful for prop info. I'm sure other specialists are as well. They sold me a nice S/S prop 14X19, and I now get about 42mph at 4,500 rpm. It's been in use for a year with no change in performance.

Speedo's, you might like to ask for a GPS for Christmas. Shouldn't need it to navigate the BCN, but they make good accurate, cheapish (over the ground) speedo's.

Hope this helps, naybe someone else can give more informed comment.

 

[Guest]

Thanks for the reply.
Firstly, may I stress that I don't attempt 15 knots on the BCN!That is restricted to the lonely tidal regions of the Severn. I hate inconsiderate speeders and the damage they cause.
An inboard diesel engine in a small boat is noisy, I have insulated the engine reasonably well so that at low revs say 800-1500 its pleasant. 2000+ its a little tiresome, and at 3500-4500 its a banshee. If I can reduce the RPM required and hence the decibels and still make reasonable progress against an ebbing Severn tide then I'll be a happy man. It seem daft not to use the obvious torque available from the diesel engine.
Hmm, I like the sound of a nice shiney stainless prop. I've not got enough experience with the Enfield to know what I can and can't use on it. I've have the chance of blagging a 13" x 18 pitch SS prop from an old Mercury 75 outboard, but I don't know if its compatible. Any ideas

As for speedos just waiting for the winter to fit one, I understand its not recommended to drill bloody great holes in the hull whilst still afloat! - I'll post the name of a guy I bought a complete new 4" Smiths analogue speedo and log AND transducer for £25 inc VAT and P and P just in case anybody else would like it. He's also good for volt and ammeters at a fiver.
Jason

 

[andrewbarker]

Jason, I think Geoff's spot on with his advice. Step 1 has to be to get a prop firm to tweak your ally job. For about 35 quid you can have it tidied up & made a bit coarser. It seems to be too fine to allow the kind of revs you're getting. That will really answer your main question before you even think about stainless steel. BTW as a consistently accident prone boater I find Poole Propellers cheapest + top class.
I would keep 2 props - 1 for inland, 1 for sea, anyway.
I'd also get a GPS rather than a speedo. It's far more accurate, does a lot of other things and in the Bristol Channel speed over ground is surely more important than speed through the water??
Finally, have you done all the other performance things engine-wise such as engine flush + top oil, Slick 50 or ZX1 (better), injector ovehaul, cetane booster??

All the best

 

[tico]

Sounds to me like you are seriously underpropped.
Ring Mike Bellamy @ Lancing Marine for good advice
01273 410025

 

[Guest]

60 gee gee's from a 1600 XLD is a little optimistic...more like 50. Mike Bellamy at Lancing Marine is your man, they marinise these engines and also have a nifty little prop size calculator program to give you some idea of what should be on the boat