Picture of hull composition A27FC

[changer]

I installed a new thru hull transducer for an 1985 A27FC. This picture is the core removed ... about 15" outboard of starboard stringer ( engine space) and 12" aft of the engine space forward bulkhead....coring, but also reasonable amount of FG.....fyi

[JT48348]

Great post! Thanks so much

[Beta Don]

Interesting

That core shows the hull thickness in the engine bay area to be nearly an inch of solid fiberglass, plus the core material. The keel area about 5 feet forward of there isn't cored and it's less than half an inch thick - Ask me how I know

Don

[sail149]

Great photo, was this a boat with a molded inner liner under the engine? (83 did not ,84 did ,85?)
I dont like to be a kill joy, and it certainly looks encouraging. But it would be interesting to analyze more carfully.
What I see is 1/4"hull skin,
1/2" balsa core with questionable bond to skin,
3/16-1/4" backup behind the core,
then 1/2" of possibly a fiberglass mush/thick mix , ( doesn't look as dense as fiberglass laminate)
then a thin layer of glass 3/32". ( or is it the inner liner?)
You suggest the plug was not from an area of multiple overlap near a bulkhead or stringer so prehaps it was a thick backup pad of mush/thick mix for a shelf for a tank/ battery. Or thru hull never installed?

If it was a boat with a liner then you might be seeing the putty/mush/thick mix used between to liner and the hull.
My boat has the liner cutaway where the hull fittings are.

Definitely encouraging........since......
My hull at the side of the keel is less than 1/8" thick. So prehaps you have a good one!

BTW, the mush/thick mix or hull to deck putty is a product sometimes made by the boatyard and sometimes bought from the resin suppliers, it a mix of resin, fillers , short fibers to produce an adhesive or somethings compression pad filler. My 84' boat has a bunch of precured 1/2" slabs of this mix used as load spreading pad under deck fittings, other A27's have aluminum or even SS plates, these details vary a lot.
I would like to see the balsa core removed anywhere a fitting is put thru the hull or deck. The compression from bolts will slowly crush the balsa, cracking the gel coat , allowing the bolts to loosen, slow leaks will happen , water will enter the balsa and you will get balsa rot......you dont want that!

I do hope you have sealed the balsa where you are putting this transducer in, preferably removed it for about 1" arround the hole and replaced with solid hard polyester or epoxy putty.
At the very least a lot of underwater polysulfide or 3M5200.
Warren

[Beta Don]

Great photo, was this a boat with a molded inner liner under the engine? (83 did not ,84 did ,85?)

My '84 doesn't have the molded liner in the engine room - Rick's '84 does though, so sometime mid-year they started using it. The deck with the engine room doors is quite different on Rick's '84 from mine too

Definitely encouraging........since......
My hull at the side of the keel is less than 1/8" thick. So prehaps you have a good one!

I think they are all quite thin on the sides at the aft end of the keel - Tapping there gives a real hollow sound . . . . you can tell the glass isn't thick and the keel isn't cored

Don

[sail149]

Don
The thin keel side does work so I'm not that worried, but would like to see 1/4" to feel comfortable !
It would sort of be interesting to know exactly how the boat design/configuration changed over the years and why (cost cutting or improvements?). I can see that the liner would be an appearance thing and a way to contain the engine fluids! But the early boats like #5 Free state(Smackman) had the strange shaft tube that moved the shaft gland close to the aft engine bulkhead so maybe the liner came with that change too.
Your boat being # 116 or 16th means it might be a left over '83 that was used for mock ups and plugs for molds......thinking about your strange pilot house construction.....or just one of the first '84s but we know boat #2 was bought at the 1983 NY boat show ( and still with same owner).
I think ricks (rnmmi) is #84 so quite late for an '84... and a long way from yours!
Mine is #73 and Vic's is #74
Warren

[changer]

Thanks All. I have learned what to look for. Taking a second look at the core, I believe I can see an 1/8th " or so mush layer...hard to tell. I do believe I have the liner for ER. My liner is not away at thru hulls, but seem sold. I want to replace the Mareolon thru hulls at some point...probably take that approach.
thanks again.
doug

[Beta Don]

I wouldn't worry about the OEM Marelon thru hulls - You'll never break one, they don't seize up due to different metals corrosion and you don't need to ground them to keep them from getting eaten away by electrolysis when you plug into an AC outlet in a marina. For an equal price, I think I'd rather have them than the bronze ones and those cost about twice as much

Don

[rnummi]

Ask Don about my through hull that used Home Depot fittings. 1/4 of grab using npt and non npt threads. Pretty hairy find and a good catch by Don when he was assisting me on the hard. Goes to show you.... Trust nothing, check everything. P.S. The PO had it out on the water several times before I bought it. Really really scary upon discovery.