Foam Core in Engine Hatch

[Ambler27FC]

Removed my engine hatches for repair. Found one has the typical end grain balsa core and is in good condition, but the other has a hard foam core with significant surface crazing. I am drilling 1/2 holes in the bottom, hogging out the core to 1.5” and refilling with epoxy filler (like you would with a thru deck) to add rigidity between the top and bottom layers. Any other thoughts? It is a complex piece i would hate to rebuild.

[tego]

Evidently the foam core didn't bond very well to the FG shell. What you're doing is probably the best solution. Another way would be to drill smaller holes and inject epoxy under some pressure on each side of the core. I remember that polyester resin didn't bond worth a squat to some foam cores. Another method might be to cut the underside hatch surface around the perimeter and lift the whole inner fiberglass panel up and re-glue the foam in using slightly thickened epoxy. I'd probably try your current method though. Good Luck. Ben "87 27FC #302

[Ambler27FC]

Thanks Togo. I have only seen re-coring as a solution, but this might work if it bonds well to the top and bottom. I don’t think polyester or epoxy will bond to the foam, but it would make the foam more rigid.

[honza]

Epoxy bonds well to CoreCell - if you can find it at reasonable price in reasonable quantities. I have built a Farrier F9R in that combination. It makes strong bond in sheer loading, which is the case for a hatch (plate bending). Not always so good, if you try to peel the glass. Forget about polyester, which is not a glue (suitable for attaching parts).

[Ambler27FC]

Thanks honza. Epoxy is always my go-to, except when using gel coat. I am hoping localized bonding between the top and bottom layers will be enough, but it is an experiment.

[DesertAlbin736]

Not sure if it's applicable in your case (regular liquid resin + hardener might be more appropriate), but for many repairs I've found West System G/flex epoxy gel adhesive to work well. For small repairs it's available in small 125 ml tubes, or larger quantities from 1 quart cans up to 4.75 gallon tubs. Gelled resin & gelled hardener mix in 1:1 ratios and will stick to just about anything, including plastics if the surface is roughed up.

Not endorsing West Marine as a source per se, just an example for illustrative purposes.

https://www.westmarine.com/buy/west-sys ... ecordNum=8

Would add FWIW my Swedish built A25 is now 48 years old & so far no evidence of core delam, soft deck spots, osmotic blisters, or issues with the engine box etc.

[Ambler27FC]

That is interesting DesertAmbler. I might try that in the future. My 33 YO boat has no major issues either. There was gel coat cracking at the sharp corners (toe rails) and the window thru holes need to be improved, but all the important stuff is really solid. The engine hatches are not supported in the center, so some cracking is expected due to flex, but the foam core was a little disappointing.

[DesertAlbin736]

The engine hatches are not supported in the center

Good point. Would adding some reinforcement, for example piece of 5/8ths plywood (painted or glassed over with woven fabric & resin) glassed on or through bolted s/s bar stock or aluminum angle battens on the underside help perhaps? Just a thought.

[DCatSea]

Coincidentally, I had a convo. yesterday with an ABYC tech familiar with the 27 from way back. Seeing my very solid wood planked engine hatch he commented that earlier 27s were known for the crappiness of the said engine hatch, and that mine looked like a very solid replacement (which it is - and also heavy).
Said hatch is down for an insulation upgrade and some serious cosmetic work this winter, and I will post before and afters once the work is done.
Yes, I have capitulated on ever living long enough to rewire Mazboot, so that's why the ABYC tech was onboard. There are just too many unknown wires flopping around and it's time to de-fubar the electrics throughout.

[Ambler27FC]

I did add a few layers of csm to the center flange and some glassed over lateral beams to move loads away from center, but this won’t prevent cracks due to a soft core. I like that wood hatch idea.

[DCatSea]

I'll be in the UK until the New Year, but I will send pix as it is as soon as I get back. I'll PM them to you and post the before and afters on AOG.

[sailonset]

We have a wooden engine hatch in our '85 27FC. Most of it is probably original, although the opening having been widened, some part of it must be new. But matches well. The port side panel is hinged and swings up nicely. The panel in the middle lifts up and out (as pictured). The starboard piece sort of lifts and slides - it's wide and heavy. I plan to hinge a small part at the end and hope that the rest can be lifted out as well as "easily" as the middle one. Have to fiddle a bit with who rests on whom.
These's new insulation below all the sections, but the Yanmar is so tall that the foam is not very thick. But it's actually pretty quiet.
Best,
dge

[Ambler27FC]

Sailonset,

That is a very interesting picture! Those hatches look entirely custom to me. Looks like you’ve got a new engine underneath.

Paint is drying on my rebuild. Added lateral reinforcements, thickened the center flanges, added allot of epoxy plugs, and repaired gel-coat. Used 1.5” of sound deadening on the bottom. Also going to add a 1/4” rubber mat under the carpet on the deck - which I think will be very effective for noise reduction. Report on the results in a year or so.

[sailonset]

Hi Ambler,
I'd thought some of the hatch might be original, since different panels have different hardware. Here are the port and starboard photos:

IMG_0275c1200.jpg

IMG_0274x1200.jpg

As you can see, they cut out the ends of the opening and moved them apart. This kept the gutters in place, but they didn't fill in the gaps. Water can leak into the bay, but since the PO had a full cover, not much water came into the cockpit or pilothouse.
Yup, a Yanmar 4JH4-HTE; one of the reasons for choosing this 27. Quiet, smooth and starts instantly. I took her on a ride around Portland Harbor and all systems worked fine.
I'll put a rubber mat over it all, one of those oriental entrance mats.
Best,
dge

[Ambler27FC]

Sailonset,

Moving that drain channel on the starboard side is a hell of a thing! A professional hand must have been involved. The hardware (handles) look like reuse to me. Hinge holes on the STBD side are different though. Completing the channels (if you choose) wouldn’t be hard, but I am sure you would be careful to protect the your new engine from the dust. The forward STBD corner might want some reinforcement to re-direct loads if you decide to complete the channels.

Thanks for the photos - interesting to see how these boats have been modified.