Hull speed.

[Allan]

If you could reach your hull speed at lower revs, would that not save you fuel? ie be more efficient.
The previous owner of my boat, who had the engine fitted, originally ordered the 43hp and some options like split charging etc. As I understand things, Beta recomended the 50, as the options were standard which meant the price was the same.
Allan

 

[sailorman]

if you reach "Hull Spd" @ lower revs the enging is too big & not loaded-up as diesels prefer.

 

[Allan]

I agree with that but it is all a matter of degree. As I have said my motor runs at approx 36 hp at what I think is a comfortable speed, for me, the crew, the hull and the motor. Using a smaller motor, say 35hp, I think would strain me, the crew and the motor. I like the fact that I run around the maximum torque level. It would also use more fuel.
Allan

 

[sailorman]

we cruise as i have stated @ 6.5 > 7kts (2600rpm = 7kts) she will run day in day out @ 7kts but more econimical @ 6.5kts as with all these Kubota based engines they are very quiet & smooth.
i made my choice of engine & installed myself. you didnt /forums/images/graemlins/wink.gif

 

[Allan]

I'm very happy to agree to disagree with on this. I would also like to thank you for your interest in my post. We have both drifted a little from my original question but I don't see a problem with that. Recently too many threads have become aggressive thanks again for avoiding that.
One final point, I have bought hundreds of engines in the past and I hate the fact that some engines with lager capacities are much more expensive even though they have exactly the same number of parts etc.
Allan

 

[sailorman]

This one might suit your needs /forums/images/graemlins/wink.gif

 

[Allan]

Looks a little under powered!!
A guy who used to work for me used to be an engineer in the merchant navy. He told me they used to have engines that they could isolate cylinders, remove the heads and work on one cylinder while still running the others. He also worked on engines that he had to climb into the cylinders to decoke them!
Allan

 

[Mudplugger]

Alan, I was replying to sailormans comments re: speed of the W33, and my response concerned my own experiences of the genre. However in all fairness, mine was a fin keeled ketch that looked after us exceeding well for some 16 years, but the hullspeed differential twixt the fin/twin keel version was not overly significant....about 30mins on a 12 hour trip. My apologies for not clarifying my comments sufficiently /forums/images/graemlins/blush.gif

 

[Allan]

No problem, as I have said before I have really enjoyed this thread and it has restored my faith in the forum. When I first set foot on my boat I fell in love with her and that has not changed since I have owned her. As I sail in the Bristol channel the bilge keels are a great boon. A couple of weeks ago I was sailing to Porlock, dead downwind under Genoa and cruising chute. There are pictures on the Bristol channel forum. At one point I was sailing at over 4 kts through the water with apparent wind on the stern of 2.5kts. I cant remember what the SOG was (the tide would have been behind us) but two thirds of apparent wind works for me! I have also found ways of getting her to head up pretty well recently.
Allan

 

[silver-fox]

You might find this item of interest.



http://www.boatdesign.net/forums/boat-design/hull-speed-1220.html

Made we reconsider some "folk" wisdom. It also backed up why I had been able to exceed max hull speed so often!