Fuel Tank Location

hmscapecod

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I was wondering if you guys had any input on fuel tank location for a 35 duffy.
1) Single center tank that would sit between the two inboard stringers vs. two long rectangular tanks, located between the inboard and outboard stringers?

Does one of these layouts offer better vessel stability on a drift?

2) If two tanks are better, is it better to go with a long rectangular tank that fits between the inboard and outbd stringers, or make a tank that is half the length and double the width, so it reaches out to the hull, sitting between the inboard stringer and hull, and straddles the outboard stringer?

Thanks!
 

F/V First Team

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U shaped tank that is joined in the center, best of both worlds. Single tank design for ease of operation, valving and the like as well as always being in trim, you wouldn't have a stagnant tank that just doesn't get used often enough to cycle the fuel in it. Plus you'd have a much greater capacity. Fun times, fun times.
 

hmscapecod

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A single center tank would be about 225 gallons, if I go with two wing tanks, i can get 350 or whatever I want. What do you mean by a U tank joined in the middle?
 

mattinri

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Are you on the Cape? You might want to check with Cape Island Boats in Orleans. They're very familiar with the Duffy 35 and very helpful.
 

BillD

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U shaped tank that is joined in the center, best of both worlds. Single tank design for ease of operation, valving and the like as well as always being in trim, you wouldn't have a stagnant tank that just doesn't get used often enough to cycle the fuel in it. Plus you'd have a much greater capacity. Fun times, fun times.

Travis,

What's the easiest fabrication for a "U" shaped tank?
Aluminum, stainless or fiberglass Travis ????

And is the "U" connection @ the back of the cockpit of mid cockpit ?

Fuel pickup? One or two and where ?
 

bluezone

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Had a 35 Duffy for many years. 300 gal in 2 tanks with an equalizing line between them. I really never used the equalizing line as I feel keeping the tanks segregated is the best way to go. That way if one tank gets contaminated you still have the other tank to get you home.
 

bluezone

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Fill was just aft of the wheelhouse and after end was afew feet from the stern.Ride was close to the same, full or slack tanks.
 

captainlarry84

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On a new build I would opt for twin side tanks as opposite to a single center tank. For starters all of the Duffys in my area have twin tanks. Duffy’s like a lot of DE boats have a nice deep center section above the shaft. It is a great place for a below deck fish hold. In the event of a shaft problem or keel problem it is a lot easier to cut a hole into a fish box than a fuel tank. In addition the side panels are pretty shallow on a Duffy so below deck storage is at a minimum for fish holds but a maximum for fuel holding.
I agree that with one tank you have no issues on turning fuel valves or maintenance. But should that tank have a problem you are unable to do anything. With twin tanks at least you get a second bite at the apple. As far as trim and old fuel goes. Every 50 gallons of running a just switch tanks. This keeps the boat in trim and your fuel fresh.
Lastly with twin tanks a 35 Duffy and hold 300 gallons of fuel.
 

captainlarry84

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A beautiful stretch up by 1st Team. And a very interesting and practical concept. It accomplishes a lot.. Very high tech.
 

hmscapecod

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I was thinking going with two tanks, they would start at about 13 feet from transom, and be 6 feet long, so they would end 9 feet from the transom. Then they would be from the inboard stringer, over the outboard stringer, and to the curve of the hull. Would be about 175 gallons each. Im just concerned that when compared to the typical tank set up of going from almost the stern to the back of the house, that maybe I am moving too much weight forward. Any thoughts on that?
 

bluezone

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If you,re worried about the weight being to far forward build the tanks shallow and long or shift the engine further aft. Weight placement is huge but a good builder will have a good idea where everything should go.
 

bluezone

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Foward end of the wheelhouse and partly into the trunk cabin. 3208 Cat.
 
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