Wood Hull Liner

[graydog]

I am in the final year of refitting a old Coronado 41 centercockpit. Now my question is the thickness of planks to use for a hull liner in my aft cabin. I have read to use 1/2 in planks which are bonded to stringers every 12". Plan to use mahogany.

What have people done that works?

[CDunc]

I fit a wood (walnut) ceiling/hull liner in my 25" Hunter. I bonded stringers every 12" and used the reflex bubble mylar insulation in between. the planks were average 2" wide but I did have to splile <sp?> them in place. I lived aboard during the Maine winters for two years and it worked wonderfully. I have no boards working loose and it all looks like the day I put them in. I would take the boards down to 3/8ths or even a Quarter so you will be able to bend them in place, and they dont put Loads against your hull that may show up in a year or so as vertical ridges on the topsides.

[boatman61]

Or you could use some ideas from here.... be a bit lighter than 1/2" planks
The Frugal Mariner: Insulating your boat

[PAR]

Bonding a ceiling in place isn't a good idea as you may need to get behind it at some point for a repair. You may need to do this in a big hurry if is a leak near or below the LWL, so consider attachment carefully.

In an idea situation you'd glue vertical strips to the hull shell or liner, then screw the ceiling pieces in place. This permits them to be removed and offers a dead air space behind them. On a wooden boat they were used as part of the ventilation system, but on a 'glass boat, like your Bill Tripp, center cockpit 'glass ride, they're just pretty.

[CDunc]

Par,

Thank you, I used the wrong wording, I should have said I bonded vertical strips not STRINGERS, and then screwed the ceiling strips to the vertical strips. I agree its not a good plan to bond the strips in place.

[cburger]

On my boats hull I used Doug Fir, leftover pieces from the local lumber yard that cost all of $20.00 to finish out an area of exposed hull near the nav station. The furring strips that I used to screw the 2" w x 1/4" thick wood strips into had to be at least 3/4" high in order to accomidate the neoprene insulation that was glued in place between them. I ripped the furring strips down to a thickness of 1/4" and then using 5 minute epoxy could push down on the strips to bend them to conform to the radius of the hull, then another two strips were laminated on top of the first to get a furring strip that had a height of 3/4", next I would laminate fiberglass strips with polyester resin over the furring strips at about four inch intervals for added bond strength. Once that was completed the insulation material was cut to fit in the spaces between the furring strips, next the Doug fir strips wher cut to fit and screwed and plugged in place and finally two coats of primer and a couple of coats of high quality marine enamal were used for a beautiful result.

1/2 inch thick mahogony boards in my opinion would be way to thick if they will be required to conform to the hull shape. The other issue with mahogony is very expensive and dark colored for an interior.

[graydog]

Thanks for all the great suggestions. I will go with 1/4" strips in a lighter colored wood.And mount them to the built up vertical strips.

This forum is great.

[PAR]

I often retro fit ceiling into boats and the two woods I prefer are cedar and white pine. I use these woods because they are light weight, very easy to mill, easy to bend and easy to finish. Cedar can be had in a lot of different colors when a customer wants a smorgasbord or pine if they want light natural or a uniform color stained match.

The general dimensions I use are 2" wide (usually scaled to the boat's other elements) by 1/2" thick. This is very light weight, but stiff enough not to sag between well spaced vertical strips.
For the vertical strips, I use two approaches. One is a blended in strip, the same color as the hull shell or liner. It's also wood, usually pine and glued in position with an adhesive/sealant, so it has some flexibility for expansion, contraction and impacts. This is painted to match the hull or liner and the ceiling is screwed to these, often using tile floor spacers (temporarily) between them, to keep even gaps. The other method is matching or contrasting wood and again I use pine, stained to match if necessary, also glued with an adhesive/sealant to the hull shell/liner. I do this because you can have quite a bit of movement from all these pieces of loosely fitted wood, the hull, the liner and the occasional hard landing on a dock or rafting. All these situations will test the pull out strength of the ceiling fasteners and the ability of the vertical strips to remain attached to the hull shell/liner. Permit flexibility or you'll pop fasteners in fairly short order.

Food for thought . . .

[SkiprJohn]

It's also a good idea to leave a bit of space between each ceiling board to allow ventilation. Building up moisture between hull and ceiling is a good start for dry rot and mildew smell.
kind regards,

[perchance]

Yellow cedar makes a good liner and finishes to a beautiful gold colour that really brightens the interior.