Fit­ting the mount­ing pads

Practical Boat Owner - - Practical -

When in­stalling com­po­nents or up­grad­ing sys­tems, it is ob­vi­ously cru­cial to be able to pro­vide se­cure mount­ing points. Some­times ex­ist­ing bulk­heads or suit­able bonded tim­ber re­in­forc­ings can be used: if not, it is nec­es­sary to fab­ri­cate suit­able sup­ports. I think a main rea­son why the heater was in­stalled in the cock­pit sole was that there was an ex­ist­ing frame­work in there to which it could be at­tached, mak­ing the job eas­ier but prone to fu­ture prob­lems.

How­ever, there was an area in the aft bat­tery locker which would pro­vide the more suit­able space re­quired. Here it would be both rea­son­ably ac­ces­si­ble and, more im­por­tantly, not as sub­ject to con­den­sa­tion from be­ing in a bilge locker. The prob­lem with this po­si­tion was that the tran­som skin lam­i­nate would not be thick enough for the fix­ings re­quired to mount the heater and elec­tronic con­trol unit. The so­lu­tion was to make up mount­ing pads, and the method shown here can be adapted for a va­ri­ety of in­stal­la­tions.


The tran­som has a slight re­verse counter, so the first job was to es­tab­lish the an­gle re­quired to shape a pad so it would fit prop­erly. This was done with a slid­ing bevel and a pro­trac­tor. If not avail­able, on a calm day a short plum bob can also be used.


The pad was made out of a sin­gle soft­wood pad, 6in wide and 5½in high. It was 1½in thick at the base and 1in thick at the top, cut at an­gle of roughly 85°. It would be bonded with a thick­ened mix of epoxy and the pad ‘tacked’ in place with fast-set­ting epoxy.


The area where the pad was to be fit­ted was washed, left to dry and masked off to the di­men­sions needed. It was abraded with 60-grit pa­per and cleaned with Sika Cleaner. The second layer of mask­ing tape at the top was put on: the strip where the fast-act­ing epoxy would be.


Mask­ing tape was then put across the top of the pad to leave a strip for the fast-act­ing epoxy after the reg­u­lar thick­ened epoxy mix had been ap­plied. It was not pos­si­ble to use hard fix­ings on the pad, so Five-Minute Ad­he­sive was used to hold it in place while the reg­u­lar epoxy cured.


To en­sure a good bond, the thick­ened epoxy mix should make con­tact with the whole sur­face; and any ex­cess squeezed out can be cleaned away af­ter­wards.


Re­move the tape while the mix is still wet. The pad was left for 24 hours to let the ad­he­sive cure. To pro­tect the pad, it was coated with a straight resin/hard­ener epoxy mix. Once the epoxy had cured, the mount­ing bracket was screwed into the pad with 4 12-gauge 25mm s/s pan-head screws.


An area was pre­pared in a sim­i­lar way to mount a wooden pad for fit­ting the elec­tronic con­trol box.


From the way the pad sat I could see that parts of the lam­i­nate were slightly ir­reg­u­lar. This isn’t a prob­lem with thick­ened epoxy de­signed to fill sur­face ir­reg­u­lar­i­ties, but a good flush bond for the fast-act­ing epoxy would be needed, and one end was bet­ter than the other for this so I used a dou­ble band of tape. The thick­ened epoxy was ap­plied first, and the clear space at the end could then be used for fast-act­ing ad­he­sive to tack the pad in place while the rest cured.


The pad for the con­trol box is bonded in place on the lam­i­nate and, once again, the epoxy is left to fully cure.

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