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Go Back   SailNet Community > General Interest > General Discussion (sailing related) > Speed
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Topic Review (Newest First)
12-19-2007 08:05 PM
sailaway21 Hull speed and hull design mean far more than displacement. For instance: 30,000SHP is sufficient to push your 1000' containership along at something over 20 knots, while it takes upwards of 120,000SHP, and another screw, to push the same vessel at speeds over 30 knots. Speed costs money, how fast do you want to go?
12-18-2007 11:27 PM
sailingdog LOL.... would seem that TB's a bit sensitive about his motorsailor's sailing abilities... BTW, I never said it didn't sail well... just that it was a motorsailor.
Quote:
Originally Posted by TrueBlue View Post
It may be a "true" motorsailor sd, but it can sail decent circles around many other mono-hulls I've encountered . . without engine power.

Like packing a very big gun under my vest, it's there when I need it and earns some respect in most of the world as a true-blue passagemaker (unlike some 28 ft tri-hull trailer-sailors I know of ).

"Best-built motorsailer in the world" they say.
12-18-2007 10:49 PM
TrueBlue
Quote:
Originally Posted by sailingdog View Post
That's why your boat is considered a motorsailor...not a true sailboat...
It may be a "true" motorsailor sd, but it can sail decent circles around many other mono-hulls I've encountered . . without engine power.

Like packing a very big gun under my vest, it's there when I need it and earns some respect in most of the world as a true-blue passagemaker (unlike some 28 ft tri-hull trailer-sailors I know of ).

"Best-built motorsailer in the world" they say.
12-18-2007 07:41 PM
jerryrlitton If the original question was speed through the water then current is irrelevant. (not counting the waves of course) If you just had a knot meter and no way of seeing land, the stars and no GPS, only your hand dragging through the water you would have no idea there even was a current. Now speed across the ground, current would matter but it is still a performance question. Same as a aircraft through the air....

Jerry
12-18-2007 07:34 PM
sailingdog That's why your boat is considered a motorsailor...not a true sailboat...
Quote:
Originally Posted by TrueBlue View Post
10 hp/ton would be considered WAY overpowered by that formula. But I have often been assured of a speedy journey during conditions with adverse currents and no wind, with our 90 hp iron genny pushing 18k lbs.
12-18-2007 06:28 PM
Cruisingdad
Quote:
Originally Posted by TrueBlue View Post
10 hp/ton would be considered WAY overpowered by that formula. But I have often been assured of a speedy journey during conditions with adverse currents and no wind, with our 90 hp iron genny pushing 18k lbs.
You are giving Macgregor's a run for their money!!! HAHA!

- CD
12-18-2007 04:47 PM
TrueBlue
Quote:
That seems to be about what most boats have, although I would say that 2 Hp for every 1000 lb (4 Hp per ton) is more like the upper limit.
10 hp/ton would be considered WAY overpowered by that formula. But I have often been assured of a speedy journey during conditions with adverse currents and no wind, with our 90 hp iron genny pushing 18k lbs.
12-18-2007 04:37 PM
Cruisingdad
Quote:
Originally Posted by CapnHand View Post
That seems to be about what most boats have, although I would say that 2 Hp for every 1000 lb (4 Hp per ton) is more like the upper limit. Our boat is 9600 lbs and has an 11 Hp diesel (2.3 Hp per ton). That being said, I've never heard anyone complain about being over powered.
I sure would not complain. THere have been many instances where a really strong current can impede if not outright stop your progress.

I have been in many blows WOT where we hardly moved at all with the wind on the nose. Other than weight, the only problem with over powering is the fuel consuption. But I wonder if a overpowered engine would hold up longer???? Not sure.

- CD
12-18-2007 04:13 PM
CapnHand
Quote:
Originally Posted by Cruisingdad View Post
I have always thought a general rule of thumb is 2 HP for every 1000 lbs. The Catalina 380 weighs about 20k and has a 40hp engine. The 400 weigs about 24000 and has a 54 hp. I would err on the high side.
That seems to be about what most boats have, although I would say that 2 Hp for every 1000 lb (4 Hp per ton) is more like the upper limit. Our boat is 9600 lbs and has an 11 Hp diesel (2.3 Hp per ton). That being said, I've never heard anyone complain about being over powered.
12-18-2007 03:48 PM
sailingdog There are way too many variables... engine size, gearing, prop diameter and pitch, hull design, etc. The best resource would be something like Dave Gerr's The Propellor Handbook.
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