I am at the planning stage of replacing some deck hatches on a sailing boat.
The framework is mitered, to prevent endgrain being open to the sea, but as
these are stepped on they also need to be strong.

I see the altenatives being miters with routed slots for loose tongues, or
mitered mortice and tennons. Anyone have any experience with this type of
work?

Thanks.

BernardR

On Sat, 27 Nov 2004 12:49:54 -0600, Bernard Randall wrote:

The framework is mitered, to prevent endgrain being open to the sea

I'm not sure this is a valid concern, since the hatches will have to be
sealed by either thick paint or thick varnish. Any unprotected wood, end
grain or not, will be damaged terminally. Strength is probably a lot more
important, and the traditional approach is to half-lap the corners, often
with a dowel through the joint for extra strength.

Sat, Nov 27, 2004, 12:49pm (EST-1)
(Bernard=A0Randall) says:
I am snip

I'da asked at news:rec.boats.building



JOAT
Measure twice, cut once, swear repeatedly.

"Ray Aldridge" wrote in message
news
On Sat, 27 Nov 2004 12:49:54 -0600, Bernard Randall wrote:

The framework is mitered, to prevent endgrain being open to the sea

I'm not sure this is a valid concern, since the hatches will have to be
sealed by either thick paint or thick varnish. Any unprotected wood, end
grain or not, will be damaged terminally. Strength is probably a lot more
important, and the traditional approach is to half-lap the corners, often
with a dowel through the joint for extra strength.

These are natural teak hatches, no paint or varnish, washed with sea water.

Bernard R

On Sat, 27 Nov 2004 14:53:52 -0600, "Bernard Randall"
wrote:


"Ray Aldridge" wrote in message
news
On Sat, 27 Nov 2004 12:49:54 -0600, Bernard Randall wrote:

The framework is mitered, to prevent endgrain being open to the sea

I'm not sure this is a valid concern, since the hatches will have to be
sealed by either thick paint or thick varnish. Any unprotected wood, end
grain or not, will be damaged terminally. Strength is probably a lot more
important, and the traditional approach is to half-lap the corners, often
with a dowel through the joint for extra strength.

These are natural teak hatches, no paint or varnish, washed with sea water.

Bernard R

Okay, obviously we're not big on salt water boating here in the
desert, but. . .

I was under the impression that even teak decking and hatches got
finished with something like spar varnish on boats. Untrue?

(BTW: Spar varnish is loverly stuff, even if you never get within a
hundred miles of salt water. I use it to protect my relief carved
signs, which are usually displayed outdoors. Stands up well to desert
sun and the occasional torrential downpour.)

--RC


Sleep? Isn't that a totally inadequate substitute for caffine?

I know I made a joint like this before. From above it looks like a
miter joint but from below, it looks like a lap joint. If your fram
is to be made 4x4 you cut all 4 pieces to 4' lengths then cut the
miters only half way throught the thickness of the work. Use a chisel
or router to remove the waste.

wrote in message
...
On Sat, 27 Nov 2004 14:53:52 -0600, "Bernard Randall"
wrote:


"Ray Aldridge" wrote in message
news
On Sat, 27 Nov 2004 12:49:54 -0600, Bernard Randall wrote:

The framework is mitered, to prevent endgrain being open to the sea

I'm not sure this is a valid concern, since the hatches will have to be
sealed by either thick paint or thick varnish. Any unprotected wood,
end
grain or not, will be damaged terminally. Strength is probably a lot
more
important, and the traditional approach is to half-lap the corners,
often
with a dowel through the joint for extra strength.

These are natural teak hatches, no paint or varnish, washed with sea
water.

Bernard R

Okay, obviously we're not big on salt water boating here in the
desert, but. . .

I was under the impression that even teak decking and hatches got
finished with something like spar varnish on boats. Untrue?

Salt water boats typically do not have any finish on the exterior teak deck
areas, this particular boat is 25yrs old and though the framework is still
good the teak strip veneer (simulated planking) that covers the marine ply
panels is wearing through.

--RC


Sleep? Isn't that a totally inadequate substitute for caffine?

Most of the hatch cover frames I've seen were either dovetailed or box jointed.
I'd recommend varnishing the hatch covers even if larger expanses of teak deck
are left to weather.



Bernard Randall wrote:

I am at the planning stage of replacing some deck hatches on a sailing boat.
The framework is mitered, to prevent endgrain being open to the sea, but as
these are stepped on they also need to be strong.

I see the altenatives being miters with routed slots for loose tongues, or
mitered mortice and tennons. Anyone have any experience with this type of
work?

Thanks.

BernardR

On Sun, 28 Nov 2004 01:04:51 GMT, wrote:

I was under the impression that even teak decking and hatches got
finished with something like spar varnish on boats.

Nope. Spar varnish is the bendy stuff (and UV proof too). As a
compromise it's thus likely to be poor on finish and abrasion
resistance. Dreadful stuff for use on deckhouses. Looks ugly when you
put it on, then gets worse with wear.

As to whether you paint something onto your decks or deckhouse trim,
then that depends on taste, money and footwear. Best stuff is
battleship grey paint, nicest looking stuff is oil. Most people go
somewhere in the middle.

The best joints IMHO for this sort of thing are a secret comb joint
under a mitre - a modern variant of secret dovetailing. There's a
square-toothed box joint cut over the inner 2/3rd of the joint and a
plain mitre outboard of that to hide the end grain. Bit slow to cut
because you need either a finger jig and a router, or you rout them
and square the ends by hand and chisel.

--
Smert' spamionam

"Andy Dingley" wrote in message
...
On Sun, 28 Nov 2004 01:04:51 GMT, wrote:

I was under the impression that even teak decking and hatches got
finished with something like spar varnish on boats.

Nope. Spar varnish is the bendy stuff (and UV proof too). As a
compromise it's thus likely to be poor on finish and abrasion
resistance. Dreadful stuff for use on deckhouses. Looks ugly when you
put it on, then gets worse with wear.

As to whether you paint something onto your decks or deckhouse trim,
then that depends on taste, money and footwear. Best stuff is
battleship grey paint, nicest looking stuff is oil. Most people go
somewhere in the middle.

In the sailing community the preference is untreated teak for all hard usage
areas and lots of varnish for all brightwork. On a boat things get banged,
dropped etc, a treatment that will quickly damage a paint or varnish coat,
added to which bare teak is a much surer underfoot than a painted surface.
I'm talking sailing boats here where you have to be on deck in all weathers
as opposed to motor boats where you can stay nice and warm in an enclosed
cabin.

The best joints IMHO for this sort of thing are a secret comb joint
under a mitre - a modern variant of secret dovetailing. There's a
square-toothed box joint cut over the inner 2/3rd of the joint and a
plain mitre outboard of that to hide the end grain. Bit slow to cut
because you need either a finger jig and a router, or you rout them
and square the ends by hand and chisel.

I wrote in an earlier post in this thread that the framework face is 1 1/2"
wide x 3/4" thick so to get a decent comb joint I would probably need a
3/16" x 1 1/4" router bit, which would be slow going at the best. I made
some CAD drawings of the loose tongue and haunched half M&T and came to the
conclusion that the M&T gave the same interlock volume as the loose tongue,
but was easier to cut the mortice using a morticer than having a special set
up to do the routing for the tongue method.

Anyway thanks all for your input.

BernardR
--
Smert' spamionam