Hi all

Went out to the boat tonight to measure up for a couple of new batteries and noticed some bulging and cracking in the fiberglass tray that they sit on which is located under the cabin floor above the encapsulated keel

I lifted the batteries and broke a bit of the loose fiberglass away and it appears that there is concrete underneath which is either the ballast or the ballast is in it

It looks to me like there was about a 3mm thick skin of fiberglass that the batteries sit on joined to thicker vertical side sections that meet up to the cabin floor

All but the rear couple of inches of the tray (that is thicker,sloped down with drain holes in it) appears to have concrete un it

My thoughts are to cut away the cracked glass in the base until i get to the good sides and then rebuild the base

I want to keep the base as thin as possible so i don't rob height from the batteries as i have only got 210 mm available at the moment and i am struggling to find a decent sized battery that is that height

I haven't any experience with fabricating anything out of fiberglass so any ideas on how to do it and join it to the existing sides would be appreciated

The other option would be to cut out the cracked base and sit a piece of rubber sheet between the concrete and the battery base and leave it that way

Sorry about the dodgy photo's as they were taken with a torch and a camera

Thanks in advance

Regards Don

I'd keep it simple. Leave it as it is or remove the fibreglass base if it'll come out without pulling thevwhole battery box out with it. Put something down on top of the concrete - even the plastic base of those green recyclable shopping bags will do... But I'd get a battery strap and mount it front to back so you can hold down yr batteries if it gets rough.

don't worry about the batts Donk , fix those toenails !!!

It doesn't look like there was any fiberglass cloth used to hold it all together.
Remove the old crap, at least as much as you can then use some epoxy to coat the concrete base and sides. If you want to level or slope the he base mix some epoxy and filler and shape it to what you want. Then before it cures paint it with some more epoxy, lay down a layer or two of 5-600gsm fiberglass cloth and wet that with epoxy using a disposable brush.
Once is cured lightly scrub it with some water and sandpaper to remove any blush then prime and paint it with your favorite paint. I'd use a 2 pack primer and paint over the new fiberglass tray as it would last forever and is acid resistant.

Are you aware of the fact, that AGM battreries can be mounted on their sides or upside down if needed? Hence your limited height in the hole.

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Harb said..
It doesn't look like there was any fiberglass cloth used to hold it all together.
Remove the old crap, at least as much as you can then use some epoxy to coat the concrete base and sides. If you want to level or slope the he base mix some epoxy and filler and shape it to what you want. Then before it cures paint it with some more epoxy, lay down a layer or two of 5-600gsm fiberglass cloth and wet that with epoxy using a disposable brush. Thi
Once is cured lightly scrub it with some water and sandpaper to remove any blush then prime and paint it with your favorite paint. I'd use a 2 pack primer and paint over the new fiberglass tray as it would last forever and is acid resistant.

Hi Harb

this is is a photo of what I broke out of the base

In the photo with the mobile phone there is a piece on its edge showing the thickness which is stuff all and appears to be 2 thicknesses of something possibly with a layer of cloth in between

Regards Don

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Donk107 said..

Harb said..
It doesn't look like there was any fiberglass cloth used to hold it all together.
Remove the old crap, at least as much as you can then use some epoxy to coat the concrete base and sides. If you want to level or slope the he base mix some epoxy and filler and shape it to what you want. Then before it cures paint it with some more epoxy, lay down a layer or two of 5-600gsm fiberglass cloth and wet that with epoxy using a disposable brush. Thi
Once is cured lightly scrub it with some water and sandpaper to remove any blush then prime and paint it with your favorite paint. I'd use a 2 pack primer and paint over the new fiberglass tray as it would last forever and is acid resistant.

Hi Harb

this is is a photo of what I broke out of the base

In the photo with the mobile phone there is a piece on its edge showing the thickness which is stuff all and appears to be 2 thicknesses of something possibly with a layer of cloth in between

Regards Don

WOW I see you also found what looks like a vintage old mobile phone down there as well.

I can't tell what type of boat you have but I don't think you have concrete there - probably glass and filler to encapsulate the ballast.
Fibreglass is really easy to work with. You just have to follow a few simple rules.
After removing the batteries you want to remove the weakened fibreglass. Use a small 4 inch grinder with a 40 grit sanding pad on it. Wear a mask and cover your cushions (remove them if possible). Grind off any loose glass and keep grinding on the vertical frames until you get to nice green or clear looking fibreglass. Stop grinding when you have 30-40mm of nice green glass on the vertical frames and bilge. Grind the bottom of the battery tray.
Then get some resin - big choice here. Probably polyester is better but if it is a hard job and you really want it to stick (and you want to paint rather than use flowcoat) use epoxy. Probably poly is best for your boat.
Put some microballoons in the resin to get it to make a nice creamy paste. Make some nice fillets around the edges of the battery base, hull and frames. Sand JUST after hardening. Like 5 minutes - don't let it get too hard. If you let it get just rubbery then don;t sand but put glass straight on.
Lay a few layers of glass down. I would recommend trying to get about 1000gm worth for a battery base. Either get two 440 double bias (double bias is great at conforming to curves) or chopped strand mat (pretty weak but fine here - not as nice to work with but much cheaper). Work in with resin consolidators and disposable brushes.
Then (if you used poly) apply some flowcoat (NOT GELCOAT - flowcoat goes off in air) and you are set. You can even glass in some pads to hold the batteries in.
Go talk to a proper resin supply place. They will give you more advice. No rocket science. Just grind out the bad and glass in the new.
cheers
Phil

I forgot to say - watch the grinder in an enclosed space like a hawk. One catch on an edge and she can spin anywhere. One grinder side will feel better - it is the side that takes the grinder away from you. Get some 40 grit sandpaper for the corners you can't get to.

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Kankama said..
I forgot to say - watch the grinder in an enclosed space like a hawk. One catch on an edge and she can spin anywhere. One grinder side will feel better - it is the side that takes the grinder away from you. Get some 40 grit sandpaper for the corners you can't get to.

And wear face mask and goggles !

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Harb said..
It doesn't look like there was any fiberglass cloth used to hold it all together.
Remove the old crap, at least as much as you can then use some epoxy to coat the concrete base and sides. If you want to level or slope the he base mix some epoxy and filler and shape it to what you want. Then before it cures paint it with some more epoxy, lay down a layer or two of 5-600gsm fiberglass cloth and wet that with epoxy using a disposable brush.
Once is cured lightly scrub it with some water and sandpaper to remove any blush then prime and paint it with your favorite paint. I'd use a 2 pack primer and paint over the new fiberglass tray as it would last forever and is acid resistant.

I would do the same as Harb. The only variation is I would flatten out the base first first with epoxy filler using clean builders sand and micro balloons about 50:50 ratio. Let it self level and when it goes off a couple of layups with cloth and epoxy. I would not waste my time with fibreglass resin. Just paint over with anything like Aldi's metal paint. I have never seen blush with the cheap epoxy I use.

Hi all

Thanks for the feedback

When i pulled the pieces of the base of box out the surface underneath looks like flat smooth concrete with a couple of cracks through it and the base of the box is not bonded to it at all

Because of the solid flat surface below the base it is tempting to cut the base out to within 10 mm on the front and sides in from the edge where the concrete like stuff is underneath (about 50mm forward of the rear of the tray and sit a piece of rubber insertion in the cut out section to level it out and sit the batteries on this

I have looked at the available space in the tray am looking at using a couple of Fullriver AGM'S (a HC50 www.fullriver.com/products/admin/upfile/HC50.pdf for the start battery and a DC85-12 on its side www.fullriverbattery.com/product/dc85-12/ for the house battery in place of the two wet cell starting batteries that are there at the moment so spillage should not be a issue and putting a strap across the top of them to hold them secure as the old ones just relied on their own weight to hold them in

I have spoken to the local supplier of these batteries and the told me that these two should be happy to be joined through the 1-2-both rotary switch that is currently fitted

I figure if i leave the perimeter of the base intact but cut out the cracked and bulging centre section it should be ok as the weight of the batteries has always been taken by the concrete looking stuff under the base

I am looking at slipping her in September so this might be a temp fix until i can construct a new base as Harb, Kankarma and Ramona suggest with fiberglass then as it is a bit of a pain doing anything on her on the mooring

I have RDO tomorrow do i might have another look in the morning to see if this will work

Regards Don

I went out today and replaced the batteries, tidied up the daggy looking lead ends and lifted all of the loose fiberglass away until i got to a solid edge

With the fiberglass removed i have exposed the concrete ballast (or the concrete around the ballast) and there is a gap on one side to the hull side and a couple of cracks in the concrete itself

The top of the concrete is fairly level but i need to level the base off a bit as i have about a 6mm ledge at the back end

I am thinking that i might mix some resin up and pour it down the gap between the concrete and inner hull to fill that up,pour some more into the cracks in the concrete to fill them, and build up the base using resin and glass mat and bond it to the inner hull sides

A mate of mine has a bit of 6 mm marine ply left over from another job so i am considering bonding it with resin to form a new flat base

Does this seem to be the correct way to go

Regards Don

That so called concrete looking stuff looks like the dry remains of spilt battery acid. In the 70's it was quite common to see the battery tray in your car covered with stuff that looks just like your very first photo.

A simple litmus paper test will confirm the PH of the white stuff.

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Warrina III said..
That so called concrete looking stuff looks like the dry remains of spilt battery acid. In the 70's it was quite common to see the battery tray in your car covered with stuff that looks just like your very first photo.

A simple litmus paper test will confirm the PH of the white stuff.

Hi Warrina

I would say that the white hard base is concrete as it is hard and solid

I think that whatever has been used as ballast as been placed inside the fiberglass hull and then concrete has been poured in to fill up the voids around it and hold it in place

If you look at the photo below my boat has a fairly thick long encapsulated keel