What is under your 22 fuel tanks? (And how's it worked out.)

Sunbeam

Hi folks,

I'm installing the new Moeller fuel tanks I got to replace my originals, and I'm interested to know what (if anything) was placed under your fuel tanks and how it has worked out.

The original fuel tanks in my boat were not installed very well, so I already know I'm not duplicating that set up. They were installed directly on the fiberglass sole - in my era boat that's also the hull - and then Starboard™ cleats were butted up against them and screwed into the hull core (ouch), with partial height Starboard cover panels attached to them. Straps were used as hold downs attached to footman loops screwed into the core on the sole. No expansion room was allowed for (Moeller recommends ~3%) and so the tank expansion had bowed the tank cover pieces and partially pulled the cleats out of the sole.

I've already got the old holes dug out and filled, so they are gone, and the new installation partially worked out and done (cleats and straps), but still have to figure out exactly what/how I'm going to put under the tanks. I heard from the builder (last summer) that they use rubber strips, and I decided I would do something like that, but I'm wondering if they will tend to move around if not glued down and/or just exactly how they have worked out. I bought a couple of sheets of rubber to cut into three or four wide strips... thinking I may use dots of 3M4000 caulk just to "encourage" them to not wiggle around under the tanks.

I considered using Dri-Dek, and did cut a leftover piece to try it, but it was kind of "slippery" so I think I'm going back to the rubber. Also it held the tanks up a bit further than necessary as compared to the cleat height. I also figure the more-compressible rubber will help slightly to support the tanks, which are specified to be completely supported (they are flat on the bottom but the hull is slightly curved).

I'll write up the installation once it's completed, but for now I'm just slightly undecided about the "under the tank" material so figured I'd see what others had and how it has worked out (or not).

Thanks,
Sunbeam

thataway · Posted: Sun Jun 30, 2013 7:48 pm Post subject:

Generally the fuel tanks on the C Dorys have lasted a good long time sitting on the floors, as long as they don't shift and abrade. The screwed in cleats were a bad idea--and a glassed in cleat which confirms to the bottom side radius of the fuel tank works very well. The 3% is to be sure that the tanks are not constrained more than that for expansion. But in the C Dory there is a strap which will allow for this much expansion. As for padding-neoprene is suggested. You don't really need to put the tanks off the bottom as you do with aluminum tanks (where you never use "rubber".

Sunbeam · Posted: Sun Jun 30, 2013 8:35 pm Post subject:

Thanks for the reply.

mgarr682

Wandering Sagebrush · Posted: Sun Jun 30, 2013 9:12 pm Post subject:

I changed my tanks attachment a bit, shortly after we bought the boat. The starboard fascia boards warped, and allowed the tanks to become malformed. I got the new style fascia boards (on warranty), and installed them. They cover the tank from bottom to top, and secure against the splash well bulkhead.

Keep your starboard for other projects, it's expensive.

Sunbeam · Posted: Sun Jun 30, 2013 10:05 pm Post subject:

Mike,

I would keep an eye on those cleats (and/or change them). Not sure if your tanks are Moeller brand, but if they are a similar material they will probably behave similarly. Moeller recommends 3% expansion room on all sides. My original tanks (another brand but also plastic) were mounted similarly to yours (minus the rubber strips) and when they expanded they pushed the cleats/screws right out of the hull. Now, there may be one difference. On my tanks there was a Starboard cover panel that was also attached to the cleat, and when the tank hit that it had extra leverage on the cleats (although it touched the cleats too). I'll see if I can post a photo and add it to the thread.

Also, the tanks are supposed to be supported all along their bottom side. Not sure if the gaps between the strips are large enough to cause a problem - it may be a non-issue (but it does answer my question about how they used the strips and why I seemed to not have enough - so thank you for that). I'm using rubber too but in my case it's mostly rubber with small gaps, vs. mostly gap.

Wandering Sagebrush: I'm not using Starboard for this at all. My original cover panels were thin starboard, but they were only 7/8 height as the original tanks extended forward of the splashwell. I now have some of the gelcoated fiberglass full cover panels and the new tanks tuck back under the splashwell, allowing them to be used (now routing the new fuel hoses is another story Angry

and one that does not yet have a happy ending!).

Thanks for the input!

Sunbeam

Sunbeam · Posted: Sun Jun 30, 2013 10:28 pm Post subject:

Here are a couple of photos of the original tank installation on my 22. This is the starboard side tank, but the port side ws the same. You can see a few things:

1) These 25-gallon tanks extended forward of the splashwell, thus allowed only partial height covers (vs. having the tops tuck up under the splashwell lip).

2) The specified room for expansion did not appear to have been allowed for, so when the tanks expanded they levered the cleats out of the sole (they were Starboard™ and screwed into the sole/core). This is one of only two places I have so far found damp core on my boat (subsequently removed). The other was the lower transom drain. This boat was stored indoors and only had 50 hours on it, so it had minimal exposure to water.

3) The tank hold-down straps ran from the top of the cover boards down to the sole at the transom behind the tanks. Seemed odd to hold something down to a free-floating decorative cover top. I'm changing that around so the new straps go from the sole (actually the angle-cleat) at the forward bottom edge to the transom near the top of the tank. So no leverage on the cover panels.

Same photo, zoomed in:

thataway · Posted: Mon Jul 01, 2013 5:35 pm Post subject:

I can see the bad design in your boat Sunbeam. My current 22 has the cleats glassed in place--and there is some small amount of room so that the tanks do not seem to damage the cleats. The 1993 boat I owned still has the original plastic tanks to my knowledge. Things change with time--but not always for the better.

Agree that plastic tanks should be supported on the bottom,but I have 50 to 60 gallon holding tanks which are not completely supported on RV's (I don't think that is a good idea)

The tanks don't have baffles, and probably should have.

The edge of the poly tanks are slightly rounded--I suggested that the glassed in cleats follow that contour.

mgarr682 If the builder has set those screws of the Starboard into epoxy, then it may be OK--but there are still potential issues with the expansion of the poly material of the tank. If not set into epoxy--there is almost guarantee that you will have core water intrusion problems at some point. A glassed in set of cleats for and athwartships is a far better way to do it. Unfortunately the factory does not aways get it right.

As for the strips under the tank--probably OK--but you will end up trapping some materials under there. I don't know how one glues starboard with 5200. Tanks are often supported on fiberglass batons or PVC lumber with 5200. However, the adherence of 5200 to Starboard is not adequate to hold tanks in place.

Grazer · Posted: Mon Jul 01, 2013 8:49 pm Post subject:

A note on the weldmount studs...
I fastened my starboard strips to the hull with weldmount studs after fixing the holes that previously held the starboard strips securing the fuel tanks. After only 2 outings I noticed one of these strips have come loose. They were only held on with 2 wm studs and smaller than I should have used. My plan now is to glass in some angled fiberglass brackets to hold the tanks in place. The three other strips held down with wm studs continue to hold, so I am not sure what happened (perhaps the bonds were compromised as they were done after the other side using the same batch).

Grazer

Sunbeam · Posted: Mon Jul 01, 2013 9:22 pm Post subject:

handmeawrench · Posted: Mon Sep 09, 2013 5:07 pm Post subject:

This isn't exactly an answer to your question...but here is my answer to the LITERAL question of "what is under your fuel tanks".

On this particular 1987 22' Angler...WET CORE.

http://s1107.photobucket.com/user/handmeawrench/media/Wet_Core.mp4.html

Glad you aren't me?

The fuel tanks were screwed directly to the hull, just like yours Sunbeam. Apparently water found its way into the core from those holes, and the rest is history.

thataway · Posted: Mon Sep 09, 2013 5:11 pm Post subject:

ouch! I hope that was not too wide spread. I'll bet that there were some screws in the floor to help hold the tank in place. Good luck on the repair.

Sunbeam · Posted: Mon Sep 09, 2013 5:26 pm Post subject:

I may not "be you" on my 22 (luckily there were just a couple of half-doller sized damp spots under the cleats), but I have been there in the past on numerous sailboats. Ugh! It's never fun, and especially when you have to "destroy" a larger area of a new-to-you boat Angry

I guess if there is a good side, it's that when its done you know the boat is better than new, and the pain fades relatively quickly (once you'e done; not during!).

To follow up on the thread (which I had forgotten to do), I put strips of rubber under the tanks, running athwartships. They are 4" wide (width runs fore-and-aft) by the width of the tanks. There are four or five strips, with something like a 1/2" to 3/4" gap between them. They are mostly held in place by the angles I used as cleats, but I also put a few dabs of 3M4000 caulk under them to keep them from wanting to move. I ordered the rubber from McMaster-Carr. It came in sheets which I cut to fit. I made strips instead of one solid sheet for a couple of reasons. One is that there are drainage channels, of sorts; and two is that it allowed me to "stretch" the sheets such that the tanks still get comprehensive support, but I didn't have to order a whole 'nother sheet just for a wee bit more to use.

I'll see if I can post photos of the whole tank setup and put them in my "Sunbeam ~ 22 Cruiser" thread.

handmeawrench: Keep us posted if you want to. We can commiserate, encourage, or just lend you an ear -- and then Thumbs Up

when you have 'er done Smile

handmeawrench · Posted: Tue Sep 10, 2013 1:55 pm Post subject:

After speaking to both the factory in Ferndale and the local C-Dory dealer I think we'll be dropping her off for a re-coring of at least the part of the deck under the fuel tanks. Yes, my friend and I can re-core and lay down epoxy and glass. But this is a bit more than the home project we wanted.

The factory pretty much agreed with thataway's guess that the water isn't too wide-spread. End grain balsa doesn't wick water very much (thank goodness).

But I won't know for sure until next week. Fingers crossed!

CDory23 · Posted: Thu Feb 19, 2015 8:07 pm Post subject:

I found this thread as I'm having issues with my tanks bulging and need to redo the supports on my twin 24gallon tanks on my 2003 22 cruiser.

"Thataway" When you say glassed in cleats are you referring to tabbing it in? If so how many tabs do you think are necessary?

My plan was to remove tanks. undercut all screw holes into core. If water damage fill with Smiths CPES, and then a hardened epoxy.

When going to reinstall I was considering using the same Starboard pieces and fiberglass tabbing them in. Is there any other ideas/improvements to this project others recommend? I didn't see there being a problem with setting the tanks back onto the core but I"m not opposed to setting them onto something.

Thanks