Bilge pump mounting plate - core issue?

[Strecker25]

We have a 98 290DA that searay has confirmed is not a cored hull. Today, while replacing bilge pumped, I removed the screws that mount the pump strainer to the bilge floor and was horrified when water started weeping out the holes. It continues to dribble out for the past hour or so, and if I stand on that section of the bilge it pushes the water out of the holes.

I drilled a small test hole through another section and it seems dry. What am I dealing with here? Is it just the mounting piece for the pumps that is likely bad? The boat passed survey 3 years ago when we bought it.

 

[Jimmy Buoy]

That will be a shelf that spans an angled part of the bottom between stringers that provides a horizontal place where items can be properly mounted. This leaves an open space below the shelf that is sometimes totally sealed on all sides and filled with expanding foam, sometimes left empty. If there are no drain holes on either end of the area any water that finds it way in there has no way to get out and can rot the shelf after enough time. It won't usually create a problem with your solid hull or the sealed stringers on either side.

 

[Strecker25]

That will be a shelf that spans an angled part of the bottom between stringers that provides a horizontal place where items can be properly mounted. This leaves an open space below the shelf that is sometimes totally sealed on all sides and filled with expanding foam, sometimes left empty. If there are no drain holes on either end of the area any water that finds it way in there has no way to get out and can rot the shelf after enough time. It won't usually create a problem with your solid hull or the sealed stringers on either side.

Thanks Jim, that's a bit of a relief. I put a shop vac on the hole and sucked out all the water. It is no longer weeping, so hopefully we're ok. I really have to question some of the work done down there by sea ray, the wire loom supports are screwed right into the stringers and are long enough to penetrate the wood core, and the holes are not filled.

Whats the best best way to check the stringers on my own? Drill a small hole? To be honest, the tap test on the interior ones sounds very hollow to me but that might just be how they are. Tapping the flat mounting surface where the engine mount is results in a definite solid thud. We have not had any alignment issues and I check it every year.

 

[Jimmy Buoy]

I've never done it, but I know others that have drilled small holes into their stringers and checked the wood coming out from the bit for soft, wet, punky wood. Just be sure to fill the holes in with 3M 5200 or 4200 to reseal screws in their holes (5200 is not to easy to free up later while 4200 can).

A friend of mine had the same boat until recently and it was a great boat, solid with little maintenance required.

 

[Strecker25]

Thanks, I'll drill a couple small holes and see what the drilled out pieces look like. Would the stringers be balsa or something harder?

 

[fwebster]

There is a piece of marine plywood that the bilge pump mounts to. It can show dark wood (wet) but still be sound so that is not a definitive test.

The concern I would have is that the plywood cannot dry out if it is sealed up. As to the source of the water, if you will look at your photo closely, you will see a crack in the bilge gelcoat leading away from the screw hole nearest where the bilge pump is sitting. In fact, you can see water leaking out of the crack, so you know water can be entering there. This is not a 5200 repair. The gelcoat needs to be ground away and the plywood examined, replaced if necessary, dried out if not, then the bilge gelcoat needs to be replaced and the bilge pump reinstalled.

Also, don't use an after market gray gelcoat. sea Ray used a special gelcoat in bilges that has a waxy component to repel water at the surface when it hardens. IT is well worth the extra $$ to use Sea Ray Bilge Coat.

 

[Strecker25]

There is a piece of marine plywood that the bilge pump mounts to. It can show dark wood (wet) but still be sound so that is not a definitive test.

The concern I would have is that the plywood cannot dry out if it is sealed up. As to the source of the water, if you will look at your photo closely, you will see a crack in the bilge gelcoat leading away from the screw hole nearest where the bilge pump is sitting. In fact, you can see water leaking out of the crack, so you know water can be entering there. This is not a 5200 repair. The gelcoat needs to be ground away and the plywood examined, replaced if necessary, dried out if not, then the bilge gelcoat needs to be replaced and the bilge pump reinstalled.

Also, don't use an after market gray gelcoat. sea Ray used a special gelcoat in bilges that has a waxy component to repel water at the surface when it hardens. IT is well worth the extra $$ to use Sea Ray Bilge Coat.

Thanks Frank. That sounds like it needs to be an offseason/on the hard job, no? I'm not too sure about grinding the bottom of the boat while its floating. If it needs to be out then maybe I can seal up the holes with 5200 for this season and tackle it in the fall.

Whats the method to remove the gelcoat and expose the plywood underneath? Can it be cut out or is grinding through the gelcoat and glass the only way?

Also, any insight on if the stringers could be impacted by a rotten bilge pump mount? It's hard to tell if the stringer wood and the bilge mount wood would have been touching prior to being glassed in so I'm not sure if it could spread into the rest of the boats structure.

 

[Strecker25]

Reviving this as were on the hard so I’m finally fixing this. I cut into the aft end of the “platform” and sure enough bunch of water that smells like shit was under there. The wood itself isn’t conpletely rotten so theoretically I could probably de-skin the plywood and let it dry but I figure I might as well just cut it all out

That being said, once I remove all the wood is it actually necessary to put a new wood platform in? I was thinking of just mounting the pumps and float switches to a piece of starboard but leaving the “V” between the stringers showing and recoating it with the searay gray bilge coat.

 

[hottoddie]

Gel coat and adhesives generally will not adhere to starboard. If you use starboard and can attach it to the hull and mount the pumps and switches to the starboard with screws then you would be fine.

 

[Strecker25]

Gel coat and adhesives generally will not adhere to starboard. If you use starboard and can attach it to the hull and mount the pumps and switches to the starboard with screws then you would be fine.

Good to know, I figured I'd be able to epoxy the starboard down. I could still just glass a smaller piece of marine plywood and get the pumps pretty close to the bottom of the V while still leaving room for water to pass underneath. I just don't see the necessity of rebuilding the "shelf" aside from just a nice level place to stand on. The trade off of rebuilding it is of course the void underneath the shelf which caused the issue in the first place. See the attached diagrams for reference of what I'm talking about in regards to the shelf.

Also, is this what I'll need to match the gray bilge gelcoat? http://www.iboats.com/Sea-Ray-1970-...l-Coat-Quart-Spectrum-Color/dm/view_id.835307

 

[hottoddie]

You could use PVC trim board such as Azek. Keep in mind that it won't hold screws very well if you tighten them too much. Should be adequate for mounting a bilge pump and float switch though.

 

[Strecker25]

You could use PVC trim board such as Azek. Keep in mind that it won't hold screws very well if you tighten them too much. Should be adequate for mounting a bilge pump and float switch though.

Cool, ill look into that. Thanks

 

[Strecker25]

I cut most of the wood out today. Not sure how I never bought a multi tool before, but it might be my new favorite toy. A carbide blade made quick work of the gel coat and glass and the wood just pulled out. The smell was GROSS, but as stated earlier by Jimmy, this wood doesn’t touch any other wood so the rot is contained. I’m going to just build it back up with plywood instead of re engineering anything, then gel coat to match

 

[Strecker25]

Repair on its way. Two new pieces of marine plywood cut to size. Laminated with west system epoxy and fused together. Then glassed in place with 4oz cloth. I ground/ chipped all loose gel coat away to make a good seal. I also cut a V shaped piece of wood to help seal the aft end so water can’t get under again. A quart of Sea Ray bilge grey is on the way for next week.

All in all not a terrible repair and I’m glad I did it right the first time.

 

[NorCal Boater]

That should work. Nice job.