P19 Fuel Tank

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grundasaurus
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P19 Fuel Tank

Post by grundasaurus »

Hello, so as we finish glassing in our stringers, we've started to think about the upcoming steps, namely the fuel tanks/system. Our first question would be whether we should go with HDPE or aluminum tanks, and if you know of any ready made tanks that would fit into the P19. We have our holes cut in the stringers for chase tubes etc as marked on the plans, now we just need to source the tank. Also, the plans seem to show two tanks end to end with a frame in the middle, but I don't really see how that would work. Any help would be much appreciated.


GV11, several rowboats, P19 in progress

ericsil
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Re: P19 Fuel Tank

Post by ericsil »

The fuel tanks are one of the toughest trade-offs you make. The aluminum tanks will not stand up forever with any salt water in the bilge. However, you can get them built in just about any configuration. The plastic tanks are tough, but they expand about 3% the first time you fill them and they need ventilation since they degas. Both are available from several sources if you check Google.

The bigger question is how to mount them. First of all there is the 3% expansion to consider. Also, the approved gas fill hoses are extremely stiff. I am not sure how you plan to route the lines though the middle of the stringers from a port on the top of the tank. I was not going to cut large notches in the top of the stringers, since they are the main structural element in the hull. I ended up routing the fill lines along the bulkheads above the sole.

The next question is the gas feed line. You want both pickup lines in the rear of each tank, since the bow will be raised most of the time. Since I had already bought a plastic tanks with the fill port and pickup on the same end of the tank, I have one tank which is not "good to the last drop" as they say. For awhile I thought about replacing the front tank with a custom build, but got so used to it I compensate automatically for the loss of range.

Lastly, you may not need two tanks. I allow 5 miles to the gallon when leaving home, although you can usually get more. In my case, that means I need a fill up for every two trips around the island or I get nervous about paddling home. If your trips are shorter and your gas station closer, you might get by with one tank.

Good luck. Most of the rest is easier.

grundasaurus
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Re: P19 Fuel Tank

Post by grundasaurus »

Thanks for the reply Eric, Would it be possible to go into a bit more detail about how you routed your fill lines? we're thinking about going with a custom aluminum tank for customization, I also like the idea of baffles to prevent too much fuel from sloshing around and unbalancing the boat. Also, Jacques if you have any input regarding the fuel system in general that would be much appreciated as the plans do not provide much detail on the system. I got a quote from a custom tank builder, is 73"x18.5"x9.5" too long of a tank? We've given up dropping the floor between the stringers in the pilothouse as we need some more weight forward to compensate for the bracket. All in all the fuel system generally leaves me scratching my head as I am pretty much only used to portable tanks etc.
Thanks
Liam.
GV11, several rowboats, P19 in progress

TomW1
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Re: P19 Fuel Tank

Post by TomW1 »

Just one slight correction to Eric's post. The new plastic tanks no longer outgas due to a change in the laws.
Restored Mirror Dinghy, Bought OD18 built by CL, Westlawn School of Yacht Design courses. LT US Navy 1970-1978

ericsil
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Re: P19 Fuel Tank

Post by ericsil »

If you are going with aluminum I think there is a good choice available almost off the shelf which will avoid the mistake I made. I used the Moeller Marine Below Deck Permanent Fuel Tank (25-Gallon, 47" x 18.03" x 7.5") which is sold by Amazon. Notice that the fill tube is straight up and the fill and fuel pickup are on the same end. This is not problem for me on the rear tank, since I have a full width bench seat on the back of the boat that covers the short exposed section of fill line. However, I am assuming, that you will want most of your fuel in a front tank, to counterbalance the bracket. In that location getting my fill line to the port side deck involved a path above the sole against the bulkhead.

One good solution for you is with http://www.rdsaluminum.com/marine-stock-below.html. Their 59181 - 30 gallon, Belly Tank has a horizontal fill inlet and a rear pickup. If asked, they will point the fill to the side where you should find a decent path under the sole. You will then have 30 gal supply, good to the last drop. As for the rear tank, it depends a lot on the range you want but you might be satisfied with a smaller backup supply that is easier to mount.

Lastly, don't forget the antisyphon barbs on the fuel lines.

ericsil
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Re: P19 Fuel Tank

Post by ericsil »

P.S. Forget the baffles, you don't need them. The total change in balance from fuel going from one end to the other in the tank is small compared to the wave action that is causing it.

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Re: P19 Fuel Tank

Post by jacquesmm »

Small tanks do not need baffles, large ones are built with baffles.
The location of the tank matters: put the tank CG under the feet of the skipper, just behind the console. If you have an extra heavy engine or a bracket, move the tank somewhat forward.
The material is up to you, I like rotomolded tanks like the ones from Moeller.
Put the tanks on platform, strap down. Follow the tank manufacturer instructions, most metallic tanks will require a neoprene pad. Same for fill, venting and other connections, tanks come with instructions unless it is a custom tank but even in that case, the fabricator will help you.
Or see:
http://newboatbuilders.com/pages/fuel.html
Jacques Mertens - Designer
http://boatbuildercentral.com

TomW1
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Re: P19 Fuel Tank

Post by TomW1 »

Also if you go aluminum check Speedytanks.com they coat there tanks which will last longer. They also will put the type and place the fittings where you want them. If you can't find what you want they will build it for you it, Cracker Larry has bought several tanks from them.
Restored Mirror Dinghy, Bought OD18 built by CL, Westlawn School of Yacht Design courses. LT US Navy 1970-1978

seaslug
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Re: P19 Fuel Tank

Post by seaslug »

I used Speedy Tanks for my little 5 gallon tank. they were very nice and accommodating throughout the process, and built my tank exactly as I requested. I found another supplier, and received one of their stock Aluminum tanks in 3 days, and it's a beautiful tank. It's not epoxy coated, but I can Awlgrip it if I want. I Awlgripped a custom tank I had built for my Sailboat, and after 13 years it looked as good as the day I painted it. The company is Boyd Welding, 352-447-2405, and they're in Ocala Florida. They have a selection of stock tanks, and also build custom tanks.

ericsil
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Re: P19 Fuel Tank

Post by ericsil »

Wow! That's several great choices I did not know about 9 years ago. Almost makes me want to cut out my front tank and drop in a replacement. Almost, that is.

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