# What kind of boat is this?

Discussion in 'Boat Design' started by parkland, Nov 5, 2014.

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### parklandSenior Member

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### parklandSenior Member

Also a side question,

How much does propeller angle change efficiency?
If the prop and shaft layed at 90* perfectly horizontal, and you get 100% effective thrust, would 15,20,or 30 degrees of angle pointing down, reduce efficiency sort of linear to the angle?

What I'm trying to say, is if the prop was pointing straight down, you would get 0% thrust, and if it was pointing straight back, you would get 100% thrust, can you just extrapolate between that?

45* angle means 50% thrust lost to downward thrust?

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### TANSLSenior Member

Among other factors unknown to me, will be proportional to the cosine of the angle of inclination of the axis.

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### gonzoSenior Member

Usually 15 degrees is considered the maximum. Most inboard setups are less than 10. The downwards angle provide some lift to the stern, which may or may not be good.

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### daiquiriEngineering and Design

The description of the boat says "Steel plaining hull" which, apart the wrong spelling of the word "planing", puzzles me. No weight is given there, but with all that superstructure and enclosed volume it surely looks pretty heavy for it's length. So, if it is indeed a planing boat, it will imo be a fuel-guzzler. And hence, not a trawler. You should check it out before making a decision.

You should also have the structures and engine surveyed by a competent person. A 23-yrs old steel boat has to be approached with a due caution.

Besides that, that boat has a rather low freeboard, a big windage, a shallow vee bottom and apparently a rather high CoG. So it will imo be suitable only for protected waters not exposed to strong winds.

Cheers

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### tom28571Senior Member

Ditto what Daquiri said. No steel boat of this size is going to plane with the listed four cylinder diesel engine. How it performs at displacement speed in terms of fuel efficiency is probably not the best as the stern will surely be down in the water causing drag. It might well have been used as a trawler but the engine sounds small for that as well.

It could be an economic choice for cruising if the fuel use is not too high. It has survived for over 20 years so seaworthyness is probably OK for the area. \$10,000 is cheap for all that volume if that is what you are looking for and commissioning costs are not too high. All those rails and lifelines might mean that it does roll from that upper works weight.

One thing I noticed is that the chine is very unfair which might indicate unfairness in the bottom and create problems if it were planing.

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### parklandSenior Member

I agree it's definitely not a planing hull. It looks to me like a displacement hull, which is what I would want.

IMHO a boat thats been in use on the great lakes, is probably a pretty good boat. Despite lots of windage and possible rolling issues, if it survived there, it is probably a very seaworthy boat.

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### parklandSenior Member

it also looks bigger than 28 ft too, looks like 40 ft to me.

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### barney831New Member

Goggle Powell Shipyards, it may be one of their.

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### phrogjlf@yahooJL Frusha

Doing some digging. Looks like a charter fishing boat, especially with all that railing.

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