Fiberglass tank refit - should I cut it open?

[Terra Nova]

Originally Posted by leveche420

...I think sanding and coating the interior thru the inspection ports will be very challenging

That's why I recommended installing manhole cleanouts.

[Cheechako]

Originally Posted by leveche420

Thanks Matt!

Question... would you cut right around the perimeter (red line) or would you leave a lip (green line) to fiberglass on top of it when I put the top panel back in place?

The risk of cutting thru red line is that I may damage the bottom panel as I cut along. The downside of cutting through green line is that it will still be difficult to access that little corner in the interior.

I think I would leave a lip, probably 3" or more wide. Might be easier. I would think there would be interior tank coating products that were not epoxy, maybe some form or latex or something...? But I guess you would have heard of it.

[Matt Johnson]

Originally Posted by leveche420

Thanks Matt!

Question... would you cut right around the perimeter (red line) or would you leave a lip (green line) to fiberglass on top of it when I put the top panel back in place?

The risk of cutting thru red line is that I may damage the bottom panel as I cut along. The downside of cutting through green line is that it will still be difficult to access that little corner in the interior.

I'd do it at the green line with a 45 degree inward angle cut. You'll then be able to lay the top back into position and glass shut.

Large tank openings are great if you can get them back off without tearing up the sole or furniture around the tank. Otherwise, keeping the small openings is fine for periodic cleaning.

I'd have to go back to find the notes, but I think the Tank Clad is what we used as the final coating for ours. It did require a week cure and several washings before we used it for potable water.

Matt

[coopec43]

Originally Posted by leveche420

Is this the water based bitumen (Crommelins) product you used?:

Water Based Bitumen Paint: Waterproofing: Crommelin

I'm almost certain it is.

When I was making up my tanks I spoke to the resin supplier and told him what I was planning (to store the water in fiberglass tanks (uncoated) as my fellow boat-builders had done) and he said "NO! You go along and see a specialist paint/coating supplier".

When I contacted the supplier and told him I was wanting to build water tanks in my yacht (in situ) and did they have a suitable product he assured me they had. He then said he was a bit worried though about the cure "How much sun will it get?"

I said NO!, No!, No! none at all because it is down in the bilges. He then asked "What none at all?" That is when I decided to build separate tanks and ones that could be easily cleaned.

Here is a photo of them. The one at the front is the holding tank and has been sliced half way up, coated with about five coats of epoxy and then re-joined. The tall tanks fit down inside the keel and the others are "wing tanks". All can fit out the companionway if necessary.


Regarding the claim of manufacturers that their product is suitable for potable water it probably is if applied in suitable conditions. But down in the bilge where there is no sun and no breeze/wind circulation? (And maybe a moisty)

[coopec43]

Originally Posted by Terra Nova

That's why I recommended installing manhole cleanouts.

I agree 100%

They did a survey of boatys (on one of these forums) and asked how many people drank water out of the boat's tanks and only a third did. (The rest drank bottled water brought from shore)


Clive

[coopec43]

Originally Posted by Cheechako

I think I would leave a lip, probably 3" or more wide. Might be easier. I would think there would be interior tank coating products that were not epoxy, maybe some form or latex or something...? But I guess you would have heard of it.

I'll go along with that. I'd be suspicious about using anything that uses a "Part B Hardener" because that means it has to "cure" and the conditions may not be suitable for a satisfactory cure.


Clive

[coopec43]

Here is my holding tank cut in two as you are suggesting

[coopec43]

No doubt these two-part epoxies are good when applied in ideal conditions
Can the average amateur guarantee that?

[coopec43]

Maybe cut the top off and screw a lid to the tank (if the furniture allows)


https://banner2.kisspng.com/20180727...7227441071.jpg


Clive

[leveche420]

I went ahead and cut the top off. Plan is to sand down all old coat of gelcoat, recoat it with a safe product for potable water and fiberglass it back together. Fingers crossed... I am optimistic thought

[Pete7]

Looks good. Do you want to add a tank sender unit and gauge whilst your at it?

Just done this to our tank to take the guess work out and having to lift all the cushions to see into the clear inspection port.

Pete

[BenBowSirocco]

Hey guys,

One of the tricks I have picked up over the years to help induce a rapid full cure in a low lying bilge area or to dry out such an area for lamination is to use "Reptile Lights" purchased from a pet store. These are designed to simulate the sun in both spectrum and heat and provide a great inexpensive way to speed along a full post cure in a dark/cool and often damp area.

Leave a couple on in open "work light" sockets for a week.

I really appreciate the links to the Potable Water Coatings!

[kmacdonald]

Add a smaller tank for drinking and cooking water and just bleach the other tanks.

[leveche420]

Originally Posted by Pete7

Looks good. Do you want to add a tank sender unit and gauge whilst your at it?

Just done this to our tank to take the guess work out and having to lift all the cushions to see into the clear inspection port.

Pete

Yes, that will be great! Thanks for the suggestion. any recommendation?

[leveche420]

Originally Posted by BenBowSirocco

Hey guys,

One of the tricks I have picked up over the years to help induce a rapid full cure in a low lying bilge area or to dry out such an area for lamination is to use "Reptile Lights" purchased from a pet store. These are designed to simulate the sun in both spectrum and heat and provide a great inexpensive way to speed along a full post cure in a dark/cool and often damp area.

Leave a couple on in open "work light" sockets for a week.

I really appreciate the links to the Potable Water Coatings!

Those infrared lights work pretty good. I tried them in my garage to cure polyester resin in my garage in cold weather and it worked!!

If anyone has more recommendations for potable water coatings please go ahead and let us know. I haven't made a decision yet as to which one I am going to use...