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Old 18-09-2013, 08:54   #1
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Realistic Power Requirements

OK, I'm a cruising sailor at heart but I'm thinking of getting a small(ish) trailerable power boat for fishing and exploring...something that will get me there and back a little faster than 6 knots.

I'm looking at a 20 foot planing hull with a small cuddy cabin in case I want to overnight. Almost everything I'm looking at has 200+ horsepower. It seems a little nuts. I want to plane but I don't need to go 30+ knots.
Ideally I'd like to run with an outboard (or two) and I'd like to keep fuel consumption realistic.

Power boating is a whole new area for me. My basic question is...
What is the minimum power I need to get a 20 ft planing hull planing?

Thanks.
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Old 18-09-2013, 08:58   #2
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Re: Realistic Power Requirements

Depending on the hull around 70 hp. for max efficiency say 15 kts in all conditions at 2/3 throttle you'll need about 115. Get a four stoke for sure, but still be prepared to burn 3-4 gallons per hour as a minimum.
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Old 18-09-2013, 08:59   #3
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Re: Realistic Power Requirements

Most of the boat manufacturers will publish their recommended min and max horsepower ratings for a given boat. I suspect stocking dealers usually rig the boats with max rated horsepower.. because that's what sells best. Folks who want lots o' HP will buy boats rigged that way, and folks who don't care all that much (but can afford it) will also be OK with it...

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Old 18-09-2013, 10:14   #4
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Re: Realistic Power Requirements

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Originally Posted by ranger42c View Post
Most of the boat manufacturers will publish their recommended min and max horsepower ratings for a given boat. I suspect stocking dealers usually rig the boats with max rated horsepower.. because that's what sells best. Folks who want lots o' HP will buy boats rigged that way, and folks who don't care all that much (but can afford it) will also be OK with it...

-Chris
I agree as the manufacture for small boats have a label right on the boat that lists the max load, occupants and house power.
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Old 18-09-2013, 10:32   #5
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Re: Realistic Power Requirements

Quote:
Originally Posted by WaterKeener View Post
OK, I'm a cruising sailor at heart but I'm thinking of getting a small(ish) trailerable power boat for fishing and exploring...something that will get me there and back a little faster than 6 knots.

I'm looking at a 20 foot planing hull with a small cuddy cabin in case I want to overnight. Almost everything I'm looking at has 200+ horsepower. It seems a little nuts. I want to plane but I don't need to go 30+ knots.
Ideally I'd like to run with an outboard (or two) and I'd like to keep fuel consumption realistic.

Power boating is a whole new area for me. My basic question is...
What is the minimum power I need to get a 20 ft planing hull planing?

Thanks.
I'm in the same boat so to speak. I have been leaning towards offshore capable trailerable power catamarans and most use outboards in the range of 150 hp to 250 hp twins. They are Glacier Bay and many others. I did find one made in Poland that recommends a pair of 50 hp outboards for 20+ kt of speed.
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Old 18-09-2013, 10:44   #6
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Re: Realistic Power Requirements

Like Boatguy30 said, depends on the boat but also the load you carry. A flat bottomed, lightly built 20' with a small cuddy cabin, small fuel and water tanks and 1-2 people could probably get by with 70-80 HP. But a heavily built, deep V, with a full cabin, big fuel and water and 4-5 people might need 150 HP just to get on plane.

On the other hand, if you have a boat with higher HP than you need, doesn't mean you have to max it out every time you go cruising. Throttle back a big engine and you should get fuel mileage as good as you would with a smaller engine running at flat out. Plus you'll get longer life and probably more reliable service from an engine that you run at lower power output, especially gas engines.
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Old 19-09-2013, 03:53   #7
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Smile Re: Realistic Power Requirements

Thanks everyone for these excellent responses.
I now feel better informed and more confident about finding a power boat with the right power for my needs.
You guys are great.

For the record, the admiral and I enjoy coastal cruising on a Seafarer 30 sloop with a Westerbeke 13.
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Old 19-09-2013, 23:49   #8
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Re: Realistic Power Requirements

Cuddy in 20 feet...NOT, planing hull 20 feet...20 mph will barley keep it on plane. there will be a max HP for the boat on a plate. use 2/3 of this number, you will go faster than 20 and you will want to but that will fulfill your stated needs.
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Old 20-09-2013, 08:03   #9
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Re: Realistic Power Requirements

Quote:
Originally Posted by WaterKeener View Post
OK, I'm a cruising sailor at heart but I'm thinking of getting a small(ish) trailerable power boat for fishing and exploring...something that will get me there and back a little faster than 6 knots.

I'm looking at a 20 foot planing hull with a small cuddy cabin in case I want to overnight. Almost everything I'm looking at has 200+ horsepower. It seems a little nuts. I want to plane but I don't need to go 30+ knots.
Ideally I'd like to run with an outboard (or two) and I'd like to keep fuel consumption realistic.

Power boating is a whole new area for me. My basic question is...
What is the minimum power I need to get a 20 ft planing hull planing?

Thanks.
Have you looked at C-Dory? Super-efficient, light weight but well built and seaworthy. A 19 Angler might meet your requirements w/ 60-70 hp. If you are interested in more of a cruiser, look at the 22 Cruiser, which would need 70-90hp.
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Old 26-09-2013, 06:46   #10
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Re: Realistic Power Requirements

Thanks Richard,
Those are nice boats! You're right, the 19 looks like just the thing. Even the 16 would fit my basic requirements and has a recommended engine under 50 hp.
Boats are coming out of the water here now. I'll make researching this a winter project (along with remodeling the galley in my sailboat).
Thanks again!
Don
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