Coring thickness

[Coastalrunner]

Anybody have a core sample of a 28TE, balsa core if possible. Just wondering how thick it is.

Also the area I've read about for the transducer instalation, is that spot cored?

I should be receiving my 28 Sunday morning, but these questions have been bugging me?

Plus I need a first post.

[Carl]

Found this.

viewtopic.php?f=4&t=3074&p=18477&hilit= ... ess#p18477

[Coastalrunner]

Thanks, I was also looking, be neat to see how much was coring and how much was glass.

[joe.baar]

These photos are from 2010 when we had the malfunctioning transducer removed. Later we replaced it - on the opposite side - with an Airmar P78 in-hull that works really well.

The boat is a 1995 28TE. The hull composition within 2 feet outboard of the keel, amidships in the area of the battery compartment, was, from inside to outside: 1/8" resin and mat; 3/4" very hard tropical hardwood plywood, no voids and similar to Philippine Lauan in character, splits with difficulty and the grain has pronounced directionality; and 3/8" resin and mat. The photos are inadequate but all I have. The hole diameter is about 1 1/2".

Note that we found NO balsa, and that other parts of the hull might be built with different materials and thicknesses. Furthermore, other boats built at the same time in Albin's yard might be entirely different.

[Coastalrunner]

That's interesting, I was wondering how albin in that period handled the thru hulls and ducer areas. I would have thought it was tapered down to solid glass. Intersecting thoughts. Guess that they continued the coring to the same depth, but installed rot free wood in those areas.

Thanks

[Pitou]

The photo in this thread clearly shows the potential exposure to water possibly being able to infiltrate the core. The best procedure to eliminate this possibility is to:

1). overdrill from the inside stopping once you hit the outside fiberglass and gelcoat skin
2). tape the bottom of the hole & completely fill the hole with chopped glass and resin
3). drill the hole for the the transducer or thru hull

Following this procedure will ensure a dry hull and protect your asset. Using 5200 or other sealants are great, but using them alone will never ensure full protection.

[joe.baar]

Kevin, what sharp eyes you have. I neglected to mention that the threaded tube connecting the transducer to the boat's inside was, indeed "sealed" with 5200 or something like it - using that product should require a license - and the wood core was just slightly damp around the hole. There was no evidence of rot. My yard force-dried the area over 5 days and then plugged the hole per your item 2 and faired new glass inside and out.

Also, because the boat's second engine, a Yanmar, drives a left-hand screw and was installed after the original transducer, it was on the "wrong" side of the keel, per Airmar's instruction sheet, so I sited the new transducer on the port side, without boring all the way through the hull, and it works fine, as mentioned. Thanks for giving me the opportunity to amplify.