padding for fuel tank

I am building an 18 ft boat designed by Devlin. I am installing a 17 gal fuel tank under the sole. I am looking for ideas regarding what sort of material I might use to pad/secure the fuel tank. Its basically a fiberglass tank surrounded with a plywood box. As I am dealing with wood and fiberglass, I doubt corrosion is an issue. I haven't worked out the hold down yet either.

Any thoughts?

Dave
fuel tank.JPG
 
Dave Engstrom said:
I am building an 18 ft boat designed by Devlin. I am installing a 17 gal fuel tank under the sole. I am looking for ideas regarding what sort of material I might use to pad/secure the fuel tank. Its basically a fiberglass tank surrounded with a plywood box. As I am dealing with wood and fiberglass, I doubt corrosion is an issue. I haven't worked out the hold down yet either.

Any thoughts?

Dave

I would use the hold down system the tank manufacture offers. The tank has been designed, molded and reinforced, to accept those hold downs. You did not say what brand tank you purchased but as an example this is what Moeller Marine offers for their tanks = https://www.moellermarine.com/product-category/fuel-containment/permanent-fuel-tanks/partsaccessories-permanent-fuel-tanks/

As for padding, I would advise against the use of anything which might absorb any possible fuel leakage. Not only would any absorbed fuel present a fire hazard, the absorption of said fuel would prevent early detection of any leakage.

This source has some useful information. https://safeafloat.com/boat-builders-handbook/
 
Thank you for your reply. My tank is a 17 gallon Moeller. I ordered the hold down they offer as you suggested. Initially I wanted to make my own as a couple pieces of cheap aluminum cost nearly $40. Shipping was another $20. I do fabricate many things, but in the interest of putting this in my rear view mirror, I relented.
 
Good morning, Mr. Engstrom~


Sorry - my note was to Dave McCann.


His advice re your tank makes good sense to me; I defer to him.


All the best,


SJS


 
The boat I am building is a collaboration between Sam Devlin and myself. I gave him my specifications and he designed the hull for me. He left the insides of the boat to me as his hourly wage is quite high. He said he perferred it that way as he had several irons in the fire and was not able to spend the time right now (that was a year ago) on a complete design. (100-150 hours). This particular boat has never been built before.

But, you wanted to know "what" I am making. It is a fishing boat. Geared toward salt water salmon fishing but also fresh water Walleye and bass as well. A hybrid if you will. It will be 18' 4" long with a 7' beam. It will be powered by a 175, a 10 (for trolling) and an electric up front for bass fishing. The electric will be linked to the sonar so it will troll on its own if I set it up, or it can spot lock, retrace a track, take me to a specific place and several other things. I am installing a washdown pump, an automatic live well, and a few other gadgets to make fishing more efficient. I have gone through 22 sheets of marine plywood so far making the bulkheads and hull panels. I need more for the sole, the hard top and helm station. This will take me awhile. I am retired now so this is a "pay as I go" sort of thing.

The hull is made of 1/2 inch Meranti the bulkheads are 3/4 inch Okuma. All BS1088. There are 2 layers of glass on the exterior of the hull and one on the inside. Construction has been a bit delayed as of late as I got roped into building someone a complete kitchen. But I had enough time to get my glassing done before we start getting snow. I live in the mountains, so that comes early. I am just starting to install the gadgets. I sent Sam a queery regarding the sole construction but have not received a reply yet. In my head I seem to remember it being 1 1/2 inches thick, but I can't find that on the plans now. I want to re-confirm before I continue. 3/4 Okuma is $270 a sheet now and I would need about 7 more to 2 complete layers.

I will attach a snap shot of the boat that was taken the day we rolled it over onto the trailer. That took 6 of us.

Dave
Boat 1.jpgBoat 3.jpg
 
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Dave

She looks gorgeous and the quality is already showing. I would imagine your Cackler experience got you into this project, but the sheer size adds quite a bit of complexity to the build. Rolling her over must have taken some thinking and preparation, plus manpower.

Keep us updated on the build as you progress. Looks like one heck of a nice boat in the making.

Eric
 
Well, thank you. Yes, it is a bit of a daunting project but, its like eating an elephant: One bite at a time. But, time spent in my workshop is like therapy for me so I enjoy it. I spoke with Sam yesterday and received some direction on installing the sole. He wants me to raise the port and starboard edges up about 3/4 of an inch to create "a bowl" to channel water away from the hull seams. That is something I would have never considered on my own. The wash down pump has the potential to make things pretty wet I suppose.
 
2.JPGHere are a couple of shots of the plan. One picture is of the foam for flotation. Sam advised me not to use the 2 part expanding foam. He said he has experienced some problems with it. He suggested using the insulation foam pictured. Do you have any experience 3.JPGwith thi4.JPGs? I will be installing that soon.

Another picture is of a template I made today for the aft section. Its part of the flotation chamber covers. There are lots of compound angles there. It had me scratching my head for awhile.
1.JPG

View attachment 2.JPG
 
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