Hull Make-up

[Jeff]

Can anyone tell me what the hull of an 81' Mac 25' is. I want to mount a depth finder,by epoxing it to the hull, but the manufacturersaid to make sure it is solid fiberglass.Thanks Jeff

 

[Dave West]

Solid Stuff

Jeff,Your Mac is solid fiberglass cloth and resin, laid into the mold by hand. Your dealer is worried that it might have a core material that is a different density and that would affect the soundings taken through it.That doesn't mean that there aren't any voids in the construction ... like air bubbles. Try several positions and select the one that delivers the clearest image.Here's some propaganda:The other method of applying fiberglass is to mix just fibers in a gun and spray them into place. It's fast ... easy ... more uniform and less expensive than doing it the "Mac" way. I think the fabric method produces a stronger hull for the same weight. In any case, the Mac has some "give" to it that many find objectionable. It is still a very strong hull, capable of much more abuse than I am willing to endure.Ol' Dave ('82 Mac 25)

 

[Martin Stephani]

Transducer mounting

Jeff, I have an '82 Mac 25 and have the transducer inside the hull and it hasn't given me any problem. I mounted it using PVC pipe which I cut on an angle so it would be perpendicular to the hull bottom. The pipe is glued inside the hull and then filled with water. Then the xducer is positioned inside the pipe and the cap screwed in place. This way if I ever have to replace the xducer it's easy to remove. Good luck and happy sailing Marty

 

[NEWGATE13]

DEPTH FINDER INTERNALLY

Try out the operation of the depth finder inside the hull by placing the transducer bottom down in a plastic bag filled with water and putting this bag where you desire the depth finder to be. Turn it on and see what results you get. If the hull is not dense enough you will get poor to no depth echos. Move the bag around to see where you get the best results. That's where you should mount it. We leave ours in the plastic bag of water in the bilge below the water line near the bow of our 30 foot Catalina and it works OK that way!