Screws into fiberglass

[dlochner]

Have you visited the J30 Class Association website? They would be a prime source for boat construction and maintenance.

 

[jaysweet]

In the photo you posted, everything in the bilge is wood covered by fiberglass. The hull is cored with balsa wood and the the stringers or floor timbers are wood and covered with fiberglass. Penetrating the skins on these parts would put the wood at risk of getting wet.

When you talk about the engine bay, I'm not sure which parts of it you are describing. The two longitudinal ribs that the engine sits on are most likely wood encapsulated with fiberglass.

Epoxy is very brittle, it needs fiberglass or some other thickener to make it less brittle. Thickened West System epoxy or Jamestown Distributor's Total Boat epoxy would be good choices. Both West (SixTen) and Total Boat (Thixio) make epoxy in easy to apply cartridges this would be appropriate for this application.

To @thinwater's point about wood in the bilge being a bad idea, in general he is correct and I would agree with him. However, in this case it is not a critical or structural application, so I would be less concerned about the wood. If the wood should rot, then just grind it out and put in a new piece. If you can use a rot resistant wood like white oak this would be less of an issue.

A Weldmount stud would be the most durable and most expensive option. A piece of pine glued to the side of the bilge with HW store epoxy the least durable and cheapest option. Drilling and screwing directly into the hull the worst option and one the should be avoided at all costs.

Dave,

What I'm calling the engine bay is a pan under the engine with no connection to any bilge, certainly by design, so no oil reaches the bilge pump. The sides are tall stringers on which the engine mounts sit, and yes: I'm pretty sure they are fiberglass on top of plywood for strength. The forward wall of the engine bay is maybe 8-10" tall, and it seems to be part of the molded inner hull liner. I don't actually think it has plywood in it, as it was fairly thin, although the top of it (where the floorboards sit) _is_ backed by plywood. Immediately forward of the engine bay is a blind bilge with a couple of keel bolts (I don't know what they were thinking, not having this drain anywhere). I can reach aft and touch the thin wall of the engine bay through the blind bilge, or rather through a 3" hole in the stringer between the blind bilge and the engine bay. Immediately forward of this is the deep, true bilge where the bilge pump and more keel bolts sit. I think the weep holes which drain the bilge aft of the engine drain into the true bilge (rather than the blind bilge), but I intend to confirm this by putting some water in the weep holes when I'm back in the water.

Anyway, I went with screws to mount the lower bracket for the sea strainer, since the whole assembly is way higher than any fluid has ever been in the engine bay. I think our floorboards would almost be floating before this bracket could get wet. Usually, the engine bay/pan has, at worst, a small puddle of antifreeze or seawater from the strainer. After rainwater leaks built up during 3.5 years of being on land (and my neglect, not visiting often), I had 1" of water in the engine pan, presumably from rainwater leaks either from above (the companionway) or from overflow from the aft bilge which somehow got past the paltry 1/2" lip between the aft bilge and the engine pan (and avoided the 2 weep holes). I'm not proud of letting this build up, but it is what it is, and I paid the price by having to replace/upgrade 3 thru-hulls which were sitting in 1/2" of water for 3 years.

Your comments on epoxy are interesting. I was struck by how brittle the "marine epoxy" (from the hardware store) was after it cured, just looking at the leftover from the mixing surface. OTOH, the gelcoat leftover was quite flexible. Thanks for your insights!

Jay

 

[jaysweet]

Have you visited the J30 Class Association website? They would be a prime source for boat construction and maintenance.

No: I'll check it out. Thanks again.

 

[patrickkidd]

I came up with this wonderful solution using a piece of 1/2” plastic. 5200 on the screws, which just pierce the top layer of fiberglass on this balsa core hull. this provides a permanent platform where the appliance can be easily replaced. It may only be possible with a wood core, as there is on this J/30.

 

[dlochner]

And you only used a small amount of 5200! Which is a good thing.

 

[Revv up]

I’ve seen where guys will drill the hole oversize then fill it with thickened epoxy to protect the core then drill into the epoxy. Personally I’d do as suggested and epoxy a piece of ply or plastic and screw into that

 

[Project_Mayhem]

Use a sharp bit. The J30 has a cored hull. Drilling into it will give water a way to enter the core. It would be safer to epoxy small blocks of wood to the hull and secure the wire and hose to those blocks.

The PO of my boat drilled into the bilge to secure the pump. Water leaked into the keel, froze and left me with a fun project in the spring. I'd recommend an adhesive over screws as well