Multihull Bulkhead Refit Advice

Ah, the irony... The failure of several (non-structural) bulkheads due to being varnished and then glued is what started all of this. In fact I peeled a large piece of wood veneer off a bulkhead last week. As they had varnished the backside of the veneer, it parted from the adhesive without damage. I guess in the early 2000's everyone was trying to 'error-proof' their factories.

Rough seas? Well everyone has a storm story... Our last multi-year cruise started with a 3 day gale East of the Bahamas. Surfing down 12-16 foot waves in an overloaded cat is not soo much fun. Moral of the story is that we are ardent weather junkies now. I'm sure there were many 'popped' tabs after that experience. However, we have never seen any hull damage (visually).

Grinder in one hand, Fein Tool in the other...

Thank you for the information! It is all appreciated.

 

I think it is time to assess whether there is any failure to warrant repairs or modifications.

 

I could not agree more. As such, we are starting with the port forward cabin.

I have been connected with a young NA, who recently earned his PE. Super good guy. But our schedules have not meshed and I was slow in getting myself into gear. He is now currently involved in several high-profile projects that are consuming his time.

So I'm doing what I can while I await the refined design of the low bulkhead in the forward cabin (my 'melon masher' - if you've ever been on a 380) and the new floor plan. I'm also suspecting he will want a couple of omega stiffeners on the hulls as well... Therefore the questions. As I want to get the stuff that isn't changing done in preparation for the mods.

I would never say anything bad about the designer, nor the builder (it is what it is when she was built and this hull is tougher than me sometimes) but I will have questions about the marginal hull & deck joint as well shortly.

Regards!

 

Ogre, you realise this is a VPLP + Xavier Fay design, optimised for series production. While some details may look scary, the engineering is done for those building methods. Repairing is one thing, improving another. Simply repair what's there and be done with it. For the bulkheads you simply take out any loose putty that you find, sand the bulkhead and hullside, then fillet and tape. If the hull deck joint is similar, you do the same thing, sand the surface, round corners with epoxy bog, tape over.
Anything else is unnecessary, you will not make the boat "better".

 

agreed, make the boat good enough

sound tabbing, not shear off veneers

the meter by which I measure is will I want to be in 12 foot fast head seas with it...going further like vac bagging tabbing is wholly unneeded

 

Thank you for the response. It is always prudent to point out that (almost all) hulls are a depreciating asset. As a project manager (and my Admiral is in finance) we understand there is a balance to be struck. However, the cost of the repairs needed v. the cost of the mods (thus also including the repairs) we are performing equate to a rounding error in the value of the vessel. I have actually communicated with VPLP on several issues with our cat over the years - back before all the lawyers shut down 'owner communiques'.

Since acquiring the hull in 2007, we have put over 10,000 blue water miles on her. As such, we like the model and it suits our lifestyle on many fronts. So performing some additional work (ourselves) for personalization is not outside any realistic pragmatic bounds. Aside from the repairs, our mods entail ergonomic and space improvements for a couple (as we actually use the asset on a regular basis).

I will post an update on the hull to deck joint tomorrow, as it was a 'bear' getting the teak free. Had to be one of the best adhered pieces of wood on the entire hull!

Best Regards - Ogre

 

Oh, you're doing a remodel on the condo? (Sorry this had to be.) Pictures man, pictures. Otherwise I'm imagining a full foam/carbon interior.

What I mean by keeping improvements in check is things like omega stiffeners, wich would only be required if the structure is tired and flexes to much. Adding them to a sound hull is a waste of money and time, they don't make the boat "better". Same as glassing in all the furniture, if the hull was designed to function without it.

Personalizing and adapting it for your own specific use and preferences is something else, it makes sense if you plan to keep the boat for a while. I actually consider the hulls themself as the only stable asset (altough not a high value one), what depreciates are the systems. Those give the boat its actual value, and need periodic maintenance and replacing. Unfortunately, every system instantly becomes used the moment it is installed, so the return is poor in terms of money, and can only be measured in pleasure to the owner.

 

Hull to deck joint bedding - upgrade to epoxy (or other adhesive) or leave enough alone?

Now that the teak toe rail is off, I have the ability to open up the interface of the hull and deck. The only reason I'm contemplating this, is because I'm here (since-your-here-itise). That and the joint itself is a bit sparse on adhesive. However, it has not shown to be leaking or flexing in this area and to be truthful removing the adhesive would prove challenging. So in the spirit of preventing 'scope growth': should the OEM work be left alone or is there some wisdom to go ahead and cut out the old remaining adhesive and re-bed?

In the picture the scale is showing roughly 2.5" (6.5+ cm) of joint overlap. I am planning on replacing the wood screws with proper bolts (as they will now be visible in the finished product). I have also carefully ground back the hull termination to provide at 45 degree angle to facilitate adding 1208 biax over the joint. And the hull constantly is measuring slightly more than 0.25" (0.64cm).

Thanks for all input in advance - Ogre

 

If you haven't ground all the edge yet, adding a fillet on the edge is much easier and cleaner than grinding.

 

I would leave it alone. Right now the adhesive is strong, it will be an unpleasant job to separate, clean and reglue, you basicly have to lift the deck to do it properly (and I suspect the hull deck is integral to the bridgedeck top). If the adhesive fails you will see it by leaking. If you fillet or lightly glass the joint, this ability dissappears, and you think that no leaks means no problem.
Now if you want to properly reinforce that joint, you have to laminate a strip of the same size and thickness as the existing overlap. That's a 0.25" thick and at ~6" wide (3" on the feathered hull tab, and 3" on the deck), effectively moving the joint inward.
If you have to ever repair the joint for real, you would inject some thickened epoxy into the existing overlap, then laminate the above strap, since it makes no sense to remove the deck.

 

Thanks for the tip. Some has already been accomplished, yet some areas are virtually impossible to get into the space (corners, etc.). So for this cabin it will be a hybrid approach. And I'll post the differences between the two techniques after glassing.

Regards - Ogre

 

Thanks for the info. But I'm wanting to confirm what you wrote: to strengthen the lap joint a 0.25" thick fiberglass patch should be used. And the material should extend 3" in both directions (???).

If that is correct, that is approximately 7 layers of 1208 biax cloth. That would be around 2.2 square meters of cloth. I'm not discounting what you said, just trying to confirm this is what you meant to say.

Best Regards - Ogre

 

Happy Friday everyone!

I removed some seriously tough methacrylate tabbing this afternoon. All stuff that was not failing (and therefore super 'pleasant' to remove). But out it had to go, in preparation for fiberglass tabbing of the main forward bulkhead.

Before I crack open a bier and enjoy a beautiful Florida sunset, the Admiral wants to know if adding a portlight is feasible/prudent/sane in a Lagoon 380 hull? The forward cabins have a Lewmar Atlantic 30 portlight in the standing area of the cabin. However, over the bunk there is nothing. And honestly adding one a little forward in the space would help with air flow while at anchor. As the bunk (and the area below the bunk) really have no natural convection to prevent mildew.

Anyone have any thoughts?

From Florida to wherever y'all are tonight; I hope your healthy, safe and enjoying life!

Ogre

 

Yes that's exactly what I mean. The glass should go from the deck edge (where the ruler end is in the picture) over the end of the hull flange (where you ground), onto the deck. You are practically extending the factory hull flange another 2.5", creating a new joint next to the existing one. Total width of the new glass will be between 5-6". While 1208 can be used with epoxy, there is no benefit in the mat layer unless using polyester or vinylester.

Why did you remove sound methacrylat? Just fillet with thickened epoxy over it.

 

Ok, thank you for the clarification on this. I am using the 1208 as it best suits the recommendation from the builder. I realize the mat layer is superfluous, however it is the lighter 3/4oz version and is locally available.

The adhesive removed was a.) in my way for other tabbing, b.) the only adhesive used on that part of the bulkhead (as it is the main forward) the rest actually being 2" glass, c.) it had a rather narrow fillet (but enough that it would have not been possible to lay epoxy over it, and d.) right now all the adhesive is suspect in my eye.

In fact, I have discerned two types of adhesive/putty now. One is the more common and flexible gray material used in the observable fillets. And the other is a slightly gray-brown material that is extremely hard and brittle. I've been detecting this material on the top of the bulkheads and as standoffs for the plywood false walls. It is very brittle and has little/no adhesion left in it. Any guesses as to what is???

Regards - Ogre