"Bernard Randall" wrote in message
...
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?

A mitered glued edge is not too strong, in my experience. Could it be a
solution to build the framework with whatever strong joints you want and
then cover it with a thin (3mm / 1/8") layer with mitered edges?

Meindert

Meindert Sprang wrote:

"Bernard Randall" wrote in message
...

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?


A mitered glued edge is not too strong, in my experience. Could it be a
solution to build the framework with whatever strong joints you want and
then cover it with a thin (3mm / 1/8") layer with mitered edges?

Meindert


Interlocking dovetails would be best in wood, sealed with paint,
whatever. For ultimate strengh, metal corner reinforcements, or
moulded solid glass fiber construction.

Ultimately, I would prefer a dark tinted plexiglass cover, with
gaskets and a moulded glass or aluminum edge frame resting on the
deck, with bugscreen and ventilation arrangenets integral. Perhaps a
modified scrap aluminum storm door frame?

Terry K

"Terry Spragg" wrote in message
...
Meindert Sprang wrote:

"Bernard Randall" wrote in message
...
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?


A mitered glued edge is not too strong, in my experience. Could it be a
solution to build the framework with whatever strong joints you want and
then cover it with a thin (3mm / 1/8") layer with mitered edges?

Meindert

You are correct that a plain glued miter joint has little mechanical
strength. The joint I am refering to has been around for a long time but I
haven't had the need for it before.


Interlocking dovetails would be best in wood, sealed with paint,
whatever. For ultimate strengh, metal corner reinforcements, or
moulded solid glass fiber construction.

The top framework of the hatches are 1 1/2" wide by 7/8" thick, without the
endgrain, the correct joint would be mortice and tennons.

Ultimately, I would prefer a dark tinted plexiglass cover, with
gaskets and a moulded glass or aluminum edge frame resting on the
deck, with bugscreen and ventilation arrangenets integral. Perhaps a
modified scrap aluminum storm door frame?

Sorry I didn't make it clear in the original post, these are cockpit hatches
which double as the seats, and cover the gas, rope and general storage
areas. The 'filling' of the hatch framework is marine ply with layed deck
veneer.

Bernard R

Terry K