Help in selecting hp for fishing boat

[nabb]

Hi, I am new to this, but can some one out there tell me what horsepower is needed for a 50ft wooden fishing boat. I have got conflicting figures thrown at me and I am confused. A guy told me I need 300hp engine for that type of boat, others recommended 130-150hp engine. The boat is going to be used for coastal fishing and fitted with a side winch. No fancy stuff.
Below is the details of the boat;
LOA - 50ft (15.24m)
Waterline length - 45ft (13.716m)
Beam - 10ft (3.048m)
Daft - 4.06ft (1.237m)
Gross Tonnage - 10tonnes (22046Ib)
Displacement Hull
I have been reading about this and what i found was, for every 500Ib you will need 1hp to propel it. Therefore for 22046Ib that would give me 44.092hp. Add 50% to cater for waves, wind and current would give me 66.138hp. Is this right? I find it very minimal. Is there any formula for determining horsepower requirement for fishing boats?
Thanks. Edington

 

[swampu]

The boat in the avitar has twin 6-71's at about 238 per engine.
Length is 65'
Beam is 22'
Don't know the weight but I'm sure it's in line with any other 65' wooden boat.

 

[Phil Fill]

The Eagle is 51 ft water line, 40 + tons powered by a DD 671, 165 hp. I figure at hull, 7 to 9 knots, about 120 hp. Many 60 ft commercial fish/net boats are powered by DD 671 non turbo.

 

[DavidM]

Eddington:

Your calculations are about right, but your weight seems way low, more like 50,000 lbs or more for a 50 boat'.

I think you are going to need at least 100 hp

 

[nabb]

Eddington:

Your calculations are about right, but your weight seems way low, more like 50,000 lbs or more for a 50 boat'.

I think you are going to need at least 100 hp

djmarchard,
I was not comfortable with weight issue, thanks for pointing that out. I am going to have a word with the boat builder. I am thinking of scouting for a reliable 150hp engine.
Any Ideas?

Edington

 

[Nomad Willy]

Anybody notice the 10' beam?

My 30' Willard has a 10' beam.

I think the beam explains the displacement question.

With an aspect ratio of 5-1 .. 3 hp per ton may/will be perfectly adequate.

Find some other boats w the same AR, disp and hull type/shape and compare their power and performance.

It's easy to fall into the overpower trap.

And if your beam and disp numbers are right and if the hull is in fact a FULL disp hull 100hp would be WAY overpowered. Another factor that is a part of this is how much fish will the boat be required to pack? Ice or other loads. Is the 10 ton disp # with full load?

I hope TAD sees this thread.