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Re: dissolving/melting polyester resin?
Here's a fairly bombproof way to install a 'puck' inside of the hull
• Apply water soluble 'grease' to the surface of hull ... taking great care to not include any entrapped air (bubbles) in the 'test goo' when applying. The 'test goo' should be applied in a 'conical' shape - so that the 'goo' contain no bubbles and will automatically shed any air bubbles as its depressed onto the hull surface.
• You can use 'mayonnaise', etc. as the 'test goo'; but, air bubbles will be impossible to see.
• Overlay the puck with duct tape to hold it in place.
• Hook up the puck to your 'read out' device and 'turn it on'.
• Take the boat out and over bottoms of varying depths, the deeper the better.
• If the depths are equal to KNOWN bottom depths, then proceed to permanent mounting.
• Remove all paint and 'grime' (and any 'test goo') from the intended surface
• Lightly use an angle grinder or 'sand' the intended surface (but not deeply) ... the object is to remove any PAINT and to partly 'level' the surface (don't remove the 'curve' of hull)
• Lightly sand the face of the puck with 320 or 220 grit sandpaper
Mounting the Puck (permanently):
• Choice of 'fumed silica' thickened epoxy -OR- HigH Temp. (Clear) RTV silicone (automotive stuff) as the adhesive ... won't be totally clear but sufficient to see any air bubbles.
• Make an airless/bubble-less conical 'pile' of the final 'adhesive' --- obviously, if using a fumed colloidal silica filled epoxy you MUST be careful not to generate air bubbles when mixing. If epoxy, do not use a 'thick' amount as it may go 'exothermic' and create ..... bubbles; use a SLOW cure epoxy; and, have a bag of ice handy if it starts to 'kick' too fast (foam out).
• Very carefully push the puck into the 'pile', -Insure the 'entire' bottom surface of the puck is entirely in contact with the 'adhesive'-, then tape etc. in place, allow to fully cure.
• Repeat the testing over known 'deep' water.
The testing will validate that the puck 'will' operate sufficiently 'though' the hull.
Any air (bubbles) included in 'the glue' will degrade performance.
Expect 'degraded' depth sounder performance especially at the deeper depths.
The above is ONLY for solid fiberglass hulls; NOT to be used for 'cored' hull laminates.
If the inner surface of the hull is 'slanted', consider to build up a 'least thickness possible' angled transition piece to get the puck as close as possible to the vertical/horizontal - use the same procedure in prepping and mounting.
Removal of installed puck:
Sharp Chisel + Hammer; or, angle grinder.
Last edited by RichH; 06-02-2016 at 01:17 PM.