Sealing thru hull in ferro

[emmo]

Hi,
This is probably one for fellow ferro owner and fellow Kiwi, Wheels.
I need to fit transducers for depth sounder and log in my ferro hull,
[have not sorted how to make the hole yet], but I am wondering what would be best to seal the hole after??
I was thinking some sort of epoxy, but I am sure all the info will flow as usual,
Cheers, Emmo

[Alan Wheeler]

Hi emmo. Well firstly to the hole. Two ways you can do this. You can use a diamond hole saw. This cuts a very nice clean hole, but is the most expensive approach for a one off hole. Or you can use a small masonry drill and drill through a series of holes in the area the one big one will take up. Then simply chip away the concrete and use side cutters to cut the steel. Ummm, that would be BIG side cutters.
For the sounder transducer, you most likely will need a block to level the trany. Shape it like a boat hull. Infact the trany will most likely be that shape anyway, so copy it with the wood. The wooden block is cut one side to fit against the hull, so as the bottom side is level for the trany to fit against.
Another way to do this is to find away to hold the trany level and then build around it with epoxy mortar. The epoxy mortar will also do the sealing job as well. But the trany is in there for keeps if you do it this way. Or you can apply a grease around the trany to act as a release agent so as you can remove it when the epoxy has cured. Then use a mastic sealant to seal it back in to the hole.
And that brings me to the sealant, use a mastic, which is a sealant that does not harden. You can also use a Urathane Adhesive sealant, but what ever you use, make sure it remains plyable so as it moves with expansion and contraction of the hull, and so you can remove the trany in future years.
Does that help???

[Boracay]

When I built my RORC 32 I sealed everything with what was sold to me at the time as searching epoxy.(The idea was that it searched out the microcracks in the cement).
The stuff was very similar to what is sold today as laminating resin. (No solvent).
I'd get everthing nice and dry and warm and paint it on liberally.
Only a small amount would be needed to seal the hole. It would probably be best to apply any fairing epoxy putty before the sealer had fully set. (Sticky to cheesy?)
I'd spring for the diamond hole saw.

[Alan Wheeler]

Interesting, never heard of Searching Resin Chris.
I don't recomend using resin "watered down" with solvents, or evadure etc. It leaves a porouse matrix once the solvent has evaporated away and water can work back into it.

[Steve Kidson]

Recently installed through hulls in my ferro and used the diamond hole cutters as previously discussed; a much easier and better result than the "drill lots of little holes" approach.

Holes drilled were larger than required, but smaller than the outside flange or head of the transducer.

At the same time I made my backing plates from 18mm ply, cut holes the correct diameter for the transducer, and kept the centre piece.

Back to the boat...before anything, paint the end of the exposed reinforcing rod and mesh with cold gal or similar to seal and prevent the onset of any rust or corrosion.

Then, mix a batch of epoxy putty and work into the hole placing the ply circles in the middle of the hole and putty mix. Leave putty proud on the outside (can be sanded back later) and put a screw into the hole where pilot drill hole is if completely covered by the putty.

When the whole lot is dry, sand the outside to be fair with the hull, remove screw from pilot hole and USING THE SAME DIAMETER HOLE SAW cut the ply piece out. Your transducer should then fit neatly into the hole that is fair and solid and also seals the steel armature inside the cement hull.

Your choice of sealant can the be a personal choice, but I prefer to use Sikaflex products - have had only good experiences with them.

Fair winds and good luck

[Steve Kidson]

Recently installed through hulls in my ferro and used the diamond hole cutters as previously discussed; a much easier and better result than the "drill lots of little holes" approach.

Holes drilled were larger than required, but smaller than the outside flange or head of the transducer.

At the same time I made my backing plates from 18mm ply, cut holes the correct diameter for the transducer, and kept the centre piece.

Back to the boat...before anything, paint the end of the exposed reinforcing rod and mesh with cold gal or similar to seal and prevent the onset of any rust or corrosion.

Then, mix a batch of epoxy putty and work into the hole placing the ply circles in the middle of the hole and putty mix. Leave putty proud on the outside (can be sanded back later) and put a screw into the hole where pilot drill hole is if completely covered by the putty.

When the whole lot is dry, sand the outside to be fair with the hull, remove screw from pilot hole and USING THE SAME DIAMETER HOLE SAW cut the ply piece out. Your transducer should then fit neatly into the hole that is fair and solid and also seals the steel armature inside the cement hull.

Your choice of sealant can the be a personal choice, but I prefer to use Sikaflex products - have had only good experiences with them.

Fair winds and good luck