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  Topic Review (Newest First)
3 Days Ago 01:07 PM
travlineasy
Re: engine size

Same was true with the Walking Beam Steam Engines used during the US Civil War - single cylinder, often measuring 6-feet across and a massive fly wheel. Lots of torque from not very much horsepower. Some monster ships were moved with these engines, but they took forever to respond to increased throttle, which brought about the demise of many of those ships. BOOM!

About the last thing I would want would to be underpowered when encountering a tight situation such as an Atlantic inlet, where you need every ounce of power to overcome some weird currents. Yeah, I know all about hull speed, but that has nothing to do with this particular situation, where the only solution is power.

All the best,

Gary
4 Days Ago 03:49 AM
Capt Len
Re: engine size

Really big semi diesels were often one piston jobs. Swinging a 6 ft 2 blade pushing 35 tons .Start with lighting a blow torch (kerosene) hanging from the deckhead and 20 minutes later a blast of compressed air to set things rolling. Loved it. Great videos on u tube. Alpha rules.
4 Days Ago 11:53 PM
Shockwave With enough horsepower, you can break a boat motoring into a seaway.
4 Days Ago 11:39 PM
capta
Re: engine size

Quote:
Originally Posted by Fantail View Post
Funniest thing I heard all weekend was "1 cylinder engine".
Turns out it wasn't a punchline. The skipper has a 12hp 1 cylinder engine on his Hunter.

Not very current friendly.
I wouldn't laugh too hard. I've seen numerous older Scandinavian fishing vessels that had one cylinder (lung) engines and a 400 ton freighter. Very, very economical, if a bit noisy. Big and heavy, but terribly reliable, low RPM engines. Mind you one could stretch out and sleep on the piston of that freighter's engine!
5 Days Ago 09:28 PM
SloopJonB
Re: engine size

What size Hunter? Kind of important. I had an 8 horse one lung Yannie in my 26' Quarter Tonner (4300 Lbs) and it was about twice what I needed.
5 Days Ago 07:05 PM
Fantail
Re: engine size

Funniest thing I heard all weekend was "1 cylinder engine".
Turns out it wasn't a punchline. The skipper has a 12hp 1 cylinder engine on his Hunter.

Not very current friendly.
01-01-2016 03:24 PM
Waltthesalt
Re: engine size

I came across a handy table made up in Ted Brewer's book "Explaining Sailboat Design" Based on data provided by John Thornycroft it gives power required for sailboat auxiliaries with normal prop arrangements. You enter LWL,
displacement and speed. So my boat a cal 29 would weigh loaded about 5 tons, and have about a 25 ft waterline. The table gives 12 hp for a 6 knot speed. Which is about right for hull speed add some HP to buck wind tide and that checks with my Beta 16.
12-25-2015 09:51 PM
Capt Len
Re: engine size

Hull speed is the limiting factor for most. Thane 's bluff bow and the oft called for towing strength made me happy with 100 hp .Big improvement over original 60 ford. Doing an inlet with 40 kts on the head or mising a tide at some gonforsaken narrow is common here and I had what it takes. Not for everybody.
12-25-2015 09:29 PM
denverd0n
Re: engine size

Quote:
Originally Posted by travlineasy View Post
However, when the weather gets real nasty, that added power will allow you to plow through those towering waves and screaming winds, while the smaller engine will not.
True, but even with that there is a limit where you are only adding weight and greater fuel consumption, without doing anything to improve the sailboat's ability to move through the water. What's more, most modern sailboat's are already powered up with this in mind. A 20 hp motor is plenty to push a 10 ton sailboat at hull speed, but most 10 ton sailboats will be powered with something more like 35-45 hp. That's plenty for driving into wind and waves. Go much beyond 50 hp in a sailboat that size and it is just a complete waste.
12-25-2015 05:27 PM
travlineasy
Re: engine size

I guess I look at it a bit differently. Yep, you could double or triple the horsepower, and not go faster - that's a fact. However, when the weather gets real nasty, that added power will allow you to plow through those towering waves and screaming winds, while the smaller engine will not. Nothing complex about this. I've owned under-powered displacement hull powerboats that moved right along on calm days, but when push came to shove, those boats were in trouble. I repowered some with much larger engines, and that same boat performed much differently in the worst conditions, thus they became safer boats. I believe those same rules apply to sailboats as well.

All the best,

Gary
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