V Berth Liner (was part of Hull-Deck Joint

[jpendoley]

Regarding the vberth liner-that has been a priority of mine to replace. I'd like to lay in insulation, lightly build some ribs and then panel. What I am not sure of is what role does that liner play in supporting the vberth bunks?  Is the bunk really an extension of the liner and if the liner is removed from the hull entirely will the bunk need to then be tabbed to the hull? If so, do I need to worry about creating a weak spot or hinge point where the vberth would be reglassed to the hull? I live aboard in the winter in New England on occasion and an insulated hull is a high priority-some places are easier than others to access and the vberth looks like a likely starting place.
Jim

[Dale Tanski]

Jim,

Before I covered the sides of our V-berth in horizontal ship lap strips of North American ash, I cut some small access holes (approx. 6" x 16") in the liner just large enough to stuff insulation behind the liner.  I then screwed wood strips behind the edges of the access holes and put the cut outs from the holes back into place.  The ash paneling strips covered all of the modifications.

The inner liner does indeed hold up the outer edges of the V-birth bunks.

Dale

[P69]

Jim,


"What role does that liner play in supporting the vberth bunks?"
  The vertical part of the liner supports the bunk portion, keeps it stiff and prevents the opening (the tank access opening) from twisting (like if you twist angle iron).

"Is the bunk really an extension of the liner and if the liner is removed from the hull entirely will the bunk need to then be tabbed to the hull? "
  Yes, you need to tab the remaining liner to the hull. It will sag and the lip holding the plywood filler will twist.
  I didn't remove the entire vertical liner because I still want liner to hold the cushions in place and I want the the angle iron effect of a corner to support the length of the liner/bunk


"...do I need to worry about creating a weak spot or hinge point where the vberth would be reglassed to the hull? "

  Weak/hinge point where?  You will tab the lower the remaining liner to the hull for the full length of the liner (fore and aft) in two places.
   1. Where you made the lower cut (8" up from the horizontal bunk in my case) to stiffen the upper cut edge
   2. Lower down at the curve where the horizontal bunk curves upward to form the vertical part of the liner. These are fore and aft bonding to the hull. I don't think it will cause hinge spot or weak spots in the hull. If anything, you might create hard spots, but you need to carry the layers down the hull 6 or so inches, tapered (2", 4", 6", etc...)

The entire v berth liner from sole up to overhead is a single piece, this includes the part the I cut out, the horizontal part that forms the bunk, and the vertical part extending to the sol., It's actually part of the entire interior one-piece liner

picture of gussets: http://bodylens.com/Gallery/displayimage.php?album=34&pid=605#top_display_media

[jpendoley]

Wow! Great information guys and the diagram was really helpful. Looks like a pretty doable project, psarticularly if the tank is not being removed. Thanks!

[PeteW]

I only have one question about sawing out large sections of the V-berth liner and that is, why? If insulation is your goal why not just foam it in?

Up in my chain locker I have a triangular shaped shelf to support the chain bucket. I resisted the urge glass it in because I think any rigid glassed in gussets attached to the outer hull and especially up in the bow, create weak spots that would cause the hull to split open in the event of an impact with a rock. IMO what saves the outer hull from catastrophic damage  is its ability to flex without breaking and absorb energy upon impact. Adding plywood gussets to the outer hull creates what's know as a shear line.

Pete

[P69]

Pete, that is a good reminder to install bulkhead carefully so they don't contact the hull and create hard/chafe points and spread out the tabbing to spread the stress. Thanks.

I thought about the hard spot issue, but since the water tanks was glassed to the hull at the edges (athwartship vertical partitions and fore/aft along the top) , I figured glassing the liner and two bulkheads underneath the berth platform is no different from the water tank, which is basically the same, but with a  top.

[jpendoley]

Working with foam is tough too. It expands everywhere and inconsistently. It creates obstacles to future work and does not flow uniformly resulting in cold spots. It can also distort furniture and structural fittings if not given enough relief holes. Plus it cost a fortune.  I have gone both ways and regret ever using the stuff. Veteran of several icebox conversions.  Also, I think the existing liner is not very attractive.  Hard spots can be prevented with proper bonding procedures-at least to my mind.

[Della and Dave]

You have probably already thought of it, but in case you haven't, one function of the liner is to shield your bed from condensation on the inside of the hull.  It's more of an issue for those of us in cold humid climates, but you should consider drain holes to let condensation drain to the bilge.   

[P69]

I thought about the condensation issue (and water from hosing down the interior). That is one of the reasons I left about 8" of vertical liner, so the cushions have a barrier to push against, instead of pushing against the hull.

It is a good point, even down here on the gulf cost, we get condensation when fronts move in and out, when temps swing from 30's/40's to low 70s in a few hours.