what size engine for dinghy

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T

tom

Hi Fred

I had a Honda 7.5 on my last boat. It made very little noise. But it was heavy and it gave me a workout putting it on and off the sailboat(26') I can't imagine putting it on a dinghy!!! Oars are amazingly quiet!!!! I actually enjoy rowing our walker bay 8. If I didn't already own the little engine I probably would just row. My wife can't row worth a darn. She tends to go in circles!!!! She loves the little engine!!! She feels safer with the engine in we can better avoid getting pooped when a large powerboat passes.
 
Joe

Joe

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Jun 1, 2004
8,162
Catalina 27 Mission Bay, San Diego
Ross, okay then....

... did you have a specific motor recommendation for mjb? What if he wants to go a little bit faster than 4 kts with all 4 adults in the tender and it's a rough day in the harbor. Is hull design relevent at all?
 
Joe

Joe

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Jun 1, 2004
8,162
Catalina 27 Mission Bay, San Diego
Ross, okay then....

... did you have a specific motor recommendation for mjb? What if he wants to go a little bit faster than 4 kts with all 4 adults in the tender and it's a rough day in the harbor. Is hull design relevent at all?
 
Ross

Ross

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Jun 15, 2004
14,693
Islander/Wayfairer 30 sail number 25 Perryville,Md.
Joe, I think that the 3+hp motor

will get four adults across a choppy harbor safely and reasonably dry. pushing fast will only throw up spray and get everyone wet. of course hull design is a factor, a flat bottom will pound if pushed too fast. A pram will not have a fine entry. A round bottom will not feel as stabile initially but will be more stabile when underway.
 
Ross

Ross

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Jun 15, 2004
14,693
Islander/Wayfairer 30 sail number 25 Perryville,Md.
Joe, I think that the 3+hp motor

will get four adults across a choppy harbor safely and reasonably dry. pushing fast will only throw up spray and get everyone wet. of course hull design is a factor, a flat bottom will pound if pushed too fast. A pram will not have a fine entry. A round bottom will not feel as stabile initially but will be more stabile when underway.
 
Ross

Ross

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Jun 15, 2004
14,693
Islander/Wayfairer 30 sail number 25 Perryville,Md.
Ok Joe, I have a challange for you

Find a listing for a hard, 10 foot fiberglass dinghy with a horse power rating over five hp. That is simple enough there ought to be lots to choose from.
 
Ross

Ross

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Jun 15, 2004
14,693
Islander/Wayfairer 30 sail number 25 Perryville,Md.
Ok Joe, I have a challange for you

Find a listing for a hard, 10 foot fiberglass dinghy with a horse power rating over five hp. That is simple enough there ought to be lots to choose from.
 
Franklin

Franklin

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Jul 20, 2005
2,422
Whitby 55 Kemah, Tx
MJB

I once asked this question on a cruiser forum. Their response is important to you I think. Their response was that if I need the dinghy to be dependable in all weather conditions, then I need to get at least a 4-6 hp. Having to carry two adults and 12 gallons of water (72 lbs) and 12 gallons of fuel (I guess about the same as water) and other gear in 2-3' waves and a strong current going the other way, you will need the extra power. So, if you don't ever plan on being out in choppy seas going against a current with 4 adults, then you can get by with just a 2-3 hp outboard. Also make sure your dinghy can float 900 lbs (4x200 plus gear, fuel and outboard)....some can't.
 
Franklin

Franklin

.
Jul 20, 2005
2,422
Whitby 55 Kemah, Tx
MJB

I once asked this question on a cruiser forum. Their response is important to you I think. Their response was that if I need the dinghy to be dependable in all weather conditions, then I need to get at least a 4-6 hp. Having to carry two adults and 12 gallons of water (72 lbs) and 12 gallons of fuel (I guess about the same as water) and other gear in 2-3' waves and a strong current going the other way, you will need the extra power. So, if you don't ever plan on being out in choppy seas going against a current with 4 adults, then you can get by with just a 2-3 hp outboard. Also make sure your dinghy can float 900 lbs (4x200 plus gear, fuel and outboard)....some can't.
 
Ross

Ross

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Jun 15, 2004
14,693
Islander/Wayfairer 30 sail number 25 Perryville,Md.
Franklin, That is a wonderful set of spec's

but the best I can find for a ten foot dink is about 630 pounds, people and engine and gear. Lyn and Larry Pardey have managed in all oceans to get along with a 75 pound dry weight dink powered by oars.
 
Ross

Ross

.
Jun 15, 2004
14,693
Islander/Wayfairer 30 sail number 25 Perryville,Md.
Franklin, That is a wonderful set of spec's

but the best I can find for a ten foot dink is about 630 pounds, people and engine and gear. Lyn and Larry Pardey have managed in all oceans to get along with a 75 pound dry weight dink powered by oars.
 
C

Chris

Seems to me

that power is more important than speed, so you would want the most the dink is rated for, not to go fast but to have the reserve available in adverse conditions or if you need to tow the mother ship. IMHO Good sailing, Chris
 
C

Chris

Seems to me

that power is more important than speed, so you would want the most the dink is rated for, not to go fast but to have the reserve available in adverse conditions or if you need to tow the mother ship. IMHO Good sailing, Chris
 
Ross

Ross

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Jun 15, 2004
14,693
Islander/Wayfairer 30 sail number 25 Perryville,Md.
I can row a ten foot heavy wooden boat

in a 2 foot chop and make progress. Just how much power do you think is needed?
 
Ross

Ross

.
Jun 15, 2004
14,693
Islander/Wayfairer 30 sail number 25 Perryville,Md.
I can row a ten foot heavy wooden boat

in a 2 foot chop and make progress. Just how much power do you think is needed?
 
P

patrick

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Jun 7, 2004
944
Birch Bay Washington
If you get a bigger OB

that will allow you to plane, get the Doel fins or something similar.
 
P

patrick

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Jun 7, 2004
944
Birch Bay Washington
If you get a bigger OB

that will allow you to plane, get the Doel fins or something similar.
 
M

mjb

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Oct 12, 2005
63
Beneteau 473 Huntington, NY
outboard HP for various dinghies

Thanks everybody. I've done some more research. Here are some sample HP requirements for various 10' hard sailing dinghies: Hunter Liberty - 2.5hp, Walker Bay 10 - 3hp, Dyer 9' Dhow - 2hp, Bauer 10 - 2hp, NN10-II - 2-3hp. The average hull weight is 110 lbs. I've purchased a new NN10 dinghy which has a recommended range of 2 to 3 hp. This research combined with everybody's thoughts leads me to the conclusion that I should get an outboard in the 2hp to 3.5hp range with a weight of 27 to 38 lbs. I've started a spreadsheet comparing all available outboards with less than 4 hp. Honda has a 2hp that's air cooled with a weight of 27 lbs, Suzuki and Yamaha each have a 2.5hp that weigh 30 lbs and 37 lbs respectively. Mercury, Nissan, and Tohatsu all share the same Tohatsu engine that comes in both a 2hp and 3.5hp version that shares the same engine block and weighs 38 lbs. In the case of the Tohatsu/Nissan/Mercury - why would anybody buy the 2hp version when you can buy the 3.5hp version that has nearly the identical specs except for hp rating? Also, is the displacement, bore, and stroke important or just the HP rating? Thanks for all your help. Mike
 
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