gas tank strap alternatives?

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ferret30

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C Dory Year
2006
C Dory Model
22 Cruiser
Vessel Name
Lily Pad
I've had the tanks out for a few days to do some cleaning and so I could take a look at the gas tank hold down strap hardware.

My tanks are kept from moving side to side with a kind of glassed in curb strip. Between the top of the tanks and the underside of the motor well, there's a constant inch or so of space. I was wondering if instead of putting the strap hardware back in, if I could just wedge in a rectangle of neoprene or something sturdy in that void. That would keep the tanks from 'hopping', and also keep them grounded so the curb would continue working.

I could avoid all hull core penetrations by doing this. What do people think?
 
Sounds like we're both doing tank projects at the same time. I'm replacing my original tanks with new Moeller ones, retrofitting the hold-down system, and replacing all the hose and clamps (which of course led to removing, "un-coring," and re-bedding the fill fittings, etc. :wink:)

Like you, I considered the various options (might as well not just slavishly duplicate what was there...) I considered the "wedge from the top" method, but decided against it because the tops of the tanks (being roto-molded) are a bit "floppy." I mean, not floppy-floppy, but not rigid enough to wedge to (IMO). Of course if you had something that engaged the edges of the tanks (maybe that's what you meant) then it'd be less that way.

I'm going to go back in with something similar to what was there, but implemented differently. For the cleats (which you don't need to change - mine were screwed into the core, so they were removed, the core cut back, and the holes filled with thickened epoxy), I'm going to use fiberglass angle stock (most likely epoxied to the hull) on the forward and inboard sides. I also got some 1/4" rubber sheeting to put under the tanks.

I removed the metal footman loops that were screwed into the hull at the transom for the after end of the straps (then there was an aluminum angle screwed to the top of the forward cleat with another footman loop fastened to it for the forward part). For the hold-down function, I'm going to go back with strap, but attach it to the boat differently. I'm going to use Weld-Mount footman loops (they get glued in with methacrylate) and put the aft ones near the top corner of the tanks. It seems like a slightly preferable location in that the straps will have less ability to "parallelogram." Not that they really would, with the cleats, but since I have to choose a location, then the higher one seems like it will be slightly preferable (if, when I mock it up, the lower location seems better, then I'll go there, but still with the Weld-Mount footman loop).

Forward, I haven't decided how I'm going to attach the strap to the angle stock yet. I could use another Weld Mount footman loop, but I'm thinking I'll either cut a slot in the angle for the strap, or perhaps rivet the strap to the angle. I'm just in the "mock it up and try it" stage at the moment.

Sunbeam :hot
 
As to the strap arrangement....

My 2002 also has the hold down strap with mounts attached to the deck. I recently sealed the deck mounts from water intrusion. I have level floor panels over the rear which limits forward tank movement. My question is how much movement is present that causes concern? Is there something I need to pay more attention to?

thanks
 
As always Sunbeam gives good advice. The cleat strips on your 2006 should be glassed in (at least mine appear to be), and you can screw into the top of them without damaging the core. there will be a slight amount of working of the splash well, transom etc--I would go back with straps.
 
One advantage of straps relative to other hard and fixed ways of holding the tanks is that both gasoline and the tanks will expand/contract with heat/cold. As a result, you don't really want a rigid system keeping the plastic tanks in place.
 
rogerbum":113nzrpz said:
... both gasoline and the tanks will expand/contract with heat/cold.
Click to expand...

Good point. I noticed that on Moeller's website they recommend allowing 2-3% for expansion (and they say not to foam plastic tanks in place because of that). That came out to around 1/2", so I'm going to allow that much with my cleat (angle) placement. Even though I'm not sure the "ends" can expand that much, I may add the fiberglass front panels*, and don't want the belly of the tanks bulging out and causing interference.

Sunbeam :hot

*Although, once I saw how much space there will be above the 23-gallon tanks, I'm considering going to a Sunbrella-type fabric curtain vs. the hard panels. I could put that space to use!
 
Just got my new 1985 16 Angler repowered by Sportcraft. They did a great job, also adding a bilge pump and double batttery system, but I am not satisfied with the original tank and battery arrangement next to the transom.

It sounds like you guys are doing things right and I hope that, on completion, you will be so kind as to provide us with some pictures to go along with your descriptions.

Many thanks from Steve and Pat-C-Lou
 
thataway":2bgu3wkp said:
As always Sunbeam gives good advice. The cleat strips on your 2006 should be glassed in (at least mine appear to be), and you can screw into the top of them without damaging the core. there will be a slight amount of working of the splash well, transom etc--I would go back with straps.
Click to expand...

Our boat only has cleats on the inside edge. In front, the tanks push against the cover panels which are held in place by the permanent floor panels and the overhang under the splash well and lazarettes. So there's nothing in front to screw in to besides the floor. Also, the screws they used were about 1.5" long, and from dremeling I could tell they almost reach the outer fiberglass layer.

I did the undercut/thickened epoxy/redrill/4200 treatment yesterday, but (as has happened before), I heard a pop when the screw went in, kind of sounding like the epoxy plug cracked. I pre-drilled with a bit sized to the minor diameter of the screw, and installed the screw before the epoxy was completely hard (3 hours).

Could I cut a chunk of some kind of hard wood, coat it in epoxy, then epoxy it to the floor, then use that? Also, Sunbeam, what are the fiberglass parts you're using? I can't picture them.
 
Here are the items I'm referring to:

1) Pre-made fiberglass angle stock from www.mcmaster.com (there are more sizes out of the photo at the bottom - I just ran out of screen for my screen-shot). I use the plain green for this type of project.

fiberglass_angles.jpg


2) The Weld-Mount footman loops. These attach with methacrylate glue (available from Weld-Mount; I'm using their AT-1030). I'm using these in the battery compartment as well (putting in new batteries/system).

footman_loop.jpg


ferret30":3qmn658g said:
I did the undercut/thickened epoxy/redrill/4200 treatment yesterday, but (as has happened before), I heard a pop when the screw went in, kind of sounding like the epoxy plug cracked. I pre-drilled with a bit sized to the minor diameter of the screw, and installed the screw before the epoxy was completely hard (3 hours).
Click to expand...

Couple of thoughts:

1) It sounds like you did thicken the epoxy so it wasn't particularly brittle.

2) Another way to do it (not saying it's necessary) is to cast the fastener in place. You can wax the fastener, then put it in when the epoxy is greenish or on the way to that stage. The wax makes it removable later. This adds strength, which you probably don't need, but also would eliminate any crackling (I agree, cured epoxy doesn't act like wood when you put wood screws into it).
 
Those strap mounts look like a good solution, except that I wonder if you'd be depending on the gelcoat adhesion to the fiberglass. When I removed the existing footman loops, they managed to pull round chunks of gelcoat off the fiberglass without much effort. Of course the contact surface area is larger with those weld mount loops.
 
A few comments: My boat was started in late Oct 2005--2006 model. I have the floor boards which can be removed. There are strips glassed into the floor at the front of the tank as well as inside. The fiberglass panels on front of the tanks are screwed into the strip. There is no core (to my knowledge in the sides of the boats.

I do use a both silica and low density/medium density filler. with epoxy. The filler does allow the screw to expand the epoxy, and not crack.

I feel better if I grind off gel coat and then epoxy strips etc to the bottom of the hull. There is variable bonding of gel coat.
 
Sunbeam - I replaced the tanks in my Campion with new plastic tanks a few years ago and I remember they came with a warning not to secure them(tight) untill they were filled with gas. Apparently the first fill of gas conditions the plastic and causes it to expand.

Your tanks should come with installation instructions that will explain this.

Regards, Rob
 
Rob: The instructions I'm referring to are the Moeller instructions, and I have new Moeller tanks. (The instructions are on the website vs. packaged with the tanks.) I think it's similar for other plastic tanks as well, since the material is subject to expansion. I have got the feeling over the years (but don't know for sure) that the expansion/contraction can continue to occur over the life of the tanks, although I could see that it might be most dramatic right at first.

Ferret: I hear you on the gelcoat/adhesion. I thought of that as well, and it's true it can vary from boat to boat, and even section to section on a given boat. In some recent tests -gluing fiberglass angle to gelcoat with the Weld-Mount methacrylate - hammering on them broke the angles but never did pull them of the gelcoat or the gelcoat off the substrate. That said, since I'm just getting a feel for the Weld-Mounts/methacrylate, I'm only using them in places where a failure probably wouldn't cause an immediate disaster.

Another option (mentioned above) is to simply grind off a bit of gelcoat and then glue to the fiberglass beneath it.

I took a look at my boat's hull this afternoon in case I had mis-remembered about the through hulls, but indeed, the hull is just the usual thickness where they were installed. All glass, and maybe 5/16" to 3/8" thick (didn't measure that, but maybe I will for fun).

Sunbeam :hot
 
Sunbeam--get that boat back together! I am only about 150 miles from Powell--and don't want to miss you there!
 
thataway":1qdqigxl said:
Sunbeam--get that boat back together! I am only about 150 miles from Powell--and don't want to miss you there!
Click to expand...

I have noticed the calendar moving on ahead :shock: I think I've determined that it's not possible for me to just buy a boat and use it, without working on it :wink: (it did sound good in theory!) At least I'm to the "putting things back together" stage now :thup It's always nice to turn that corner vs. when it feels like you're continually taking the boat apart :cry

Powell or bust :D
 
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