Hydrovane external backing pads - epoxy mix rather than timber?

dgadee

dgadee

Well-Known Member
Joined
13 Oct 2010
Messages
4,745
Visit site
I am just about to finish off the installation of a hydrovane. I have internal backing pads glassed in, the lower external pad and bracket in place but the top bracket is a problem.

The hull has curves in two directions (including a difference in 30mm between left and right gaps between end of bracket and hull) and I have discarded two timber backing pieces I made as bad fit. I am wondering about whether to mix up expoxy and chopped glass, put this into a plastic bag and let it set with the bracket in place. I can then tidy it up and it should be a perfect fit for the hull.

I emailed hydrovane yesterday but thought that someone here has probably tried this in the past. If so, did it work?

They give various options to use, but not moulding a pad to fit externally, though say it could be used internally.
 
dgadee said:
I am just about to finish off the installation of a hydrovane. I have internal backing pads glassed in, the lower external pad and bracket in place but the top bracket is a problem.

The hull has curves in two directions (including a difference in 30mm between left and right gaps between end of bracket and hull) and I have discarded two timber backing pieces I made as bad fit. I am wondering about whether to mix up expoxy and chopped glass, put this into a plastic bag and let it set with the bracket in place. I can then tidy it up and it should be a perfect fit for the hull.

I emailed hydrovane yesterday but thought that someone here has probably tried this in the past. If so, did it work?

They give various options to use, but not moulding a pad to fit externally, though say it could be used internally.
Click to expand...

An interesting idea.

I take it a wooden pad bedded on a suitable sealant wont be acceptable

May be not chopped glass if you mean chop up your own glass mat as that will contain a binder soluble in polyester resin but not in epoxy.

Loads of other fillers available for epoxy, including glass, to impart different properties

Loadsa information and instructions for doing almost anything with epoxy on the Wessex resins website http://www.wessex-resins.com/westsystem/index.html
 
VicS said:
I take it a wooden pad bedded on a suitable sealant wont be acceptable

May be not chopped glass if you mean chop up your own glass mat as that will contain a binder soluble in polyester resin but not in epoxy.
Click to expand...

Sealant would be too flexible at 30mm I think. Yes, see the point re using glass mat - I have a bag of already purchased short glass strands which I presume is binder free.

Will have a look at that site.
 
Sorry was not suggesting a flat pad with a huge thickness of sealant but rather a pad shaped as closely as possible and just made good with sealant. But if that's not possible/acceptable then so be it.
 
dgadee said:
What did you use as filler? I have various available, but was thinking glass might be best.
Click to expand...

The "book" recommendation is a 50/50 mix of 406 high density and 404 collodial silica. I have used that successfully in the past. If you follow the instructions in the link above, which is a precised extract from the book, you will end up with a smooth finish - indeed you could pigment it to match the hull or paint the exposed bit. No need to use glass, which would inhibit getting a good finish. Your pad will be in compression only.
 
>I emailed hydrovane yesterday but thought that someone here has probably tried this in the past. If so, did it work?

I would wait for Hydrovane's response, they will know the loading and if what you are suggesting is feasible.
 
KellysEye said:
>I emailed hydrovane yesterday but thought that someone here has probably tried this in the past. If so, did it work?

I would wait for Hydrovane's response, they will know the loading and if what you are suggesting is feasible.
Click to expand...

When we installed a Hydrovane on our Oyster Mariner we had a similar issue, we had to discard at least two attempts at shaping blocks before we managed to make one that was close enough in shape to the profile of the transom. It was in 2006 but if I recall correctly it was simply a case of trial and error until we got a shape that fitted, there is a bed of sikaflex between the pad and the hull but bedding it is only 3-4mm. On the inside of the hull the bolts go through very large 12mm marine play pads that are glassed into the fabric of the boat to spread the load. It is all still rock solid 8 years later. Good luck, I remember how frustrating it was, but the satisfaction when we launched the boat and found that we had the position almost inch perfect was tremendous. We did have a small pile of very expensive lumps of teak that we had to find alternative uses for though.
 
KellysEye said:
>I emailed hydrovane yesterday but thought that someone here has probably tried this in the past. If so, did it work?

I would wait for Hydrovane's response, they will know the loading and if what you are suggesting is feasible.
Click to expand...

Prompt reply from them -

"Yes, I have seen such – using plastic wrappings with protective plastic wrapping the casting. An excellent idea – perfectly matches the contours."

So we have a go-er.
 
Get a piece of 1/8th plywood that is the size and shape required. Drill the hole the required size and fit it as a backing plate. Once tightened up eyeball it to see if it conforms reasonably well.

If yes, cut some more pieces to make a sandwich of the desired thickness. Butter with thickened epoxy and lightly grease the bolt. Fit in place and tighten but not to the point you squeeze out all the epoxy.

When fully cured tighten a little more.
 
You must log in or register to reply here.

Share this page

Top