Bamar Hatch rebuild

Dear All,

It's time to rebuild my deck hatches.  The original color was white.  Does anyone know what the original white was called?  I plan to have them power-coated and the local shop has a variety of whites.

Thanks,

Chris  Mabel's Casse Tete 43/003

Dear Members,

My cast aluminum Bomar hatches were originally made with a 1/4 inch lexan lens.  I have read about replacement lenses and spoken with cast acrylic and polycarbonate suppliers.  There seems to be some consensus that 3/8 or 1/2 inch cast acrylic would be a better replacement.

Any opinions?  Also, clear or white?

Thanks,

Chris

Chris
1/4 inch sounds very thin, would suggest that the hatches are rather small.
Although the European Recreational Craft Directive does not refer for your yacht the hatch standard provides a good guideline for the thickness. If you can give the size of the lens I can calculate the RCD thickness requirement.
Kind regards
Lars

Dear Professor,

Thank you for your reply.  I have attached 3 pictures of the smaller of the two hatches - the larger one is still on the boat.

The lens of the smaller one is 18inches by 13 1/4 inches by 1/4 inch

The estimated size of the lager one is 26 inches by 26 inches.  The larger hatch has 2 support bars (possibly three - can't remember) and is constructed like the smaller one pictured.

Thank you,

Chris Mabel's Casse Tete

closed hatch

Base and hatch inside

hatch inside up close

Chris
Thank you for the information.
It appears the Bomar people knew about hatch scantlings long ago.
The support bar for the smaller hatch makes the lens panels so narrow that 1/4" acrylic or polycarbonate is fine for strength. The same refers for the bigger hatch if it has three support bars.
Polycarbonate will flex a little more for the same thickness, and the RCD standard also considers it to have lower strength than acrylic.
Kind regards
Lars

Dear Professor,

Thank you for the information. I plan to visit the boat tomorrow and will remove the larger hatch at that time. Then we will know if there are 2 or 3 support bars!

I understand that cast acrylic is more scratch-resistant and in far greater use now than is lexan/poly carbonate, so I may go this way; I will let you know when I decide.

Thank you,

Chris

Dear Professor,

Good news, the larger Bomar hatch does indeed have 3 support bars. 

While attempting to disassemble the hatches, I have run into two problems about which you may be able to advise me.  First, two of the bolts were seized to the aluminum frame and broke off.  My plan is to drill them out and re-tap.  Secondly, some of the press pins are seized.  I recognize these are common problems and will continue to work on them but if you know of some tricks, I am all ears.

With warm regards,

Chris

Good news, all press pins are out and the hatches are at the machine shop; three bolts broke so I need drilling and tapping. Should get them back on Wednesday and then off to be power-coated.

I will show pictures when I have them.

Chris

Dear Members,

The power-coated hatches are finally back - the job is acceptable but not fantastic.  The owner of the shop said it was the combination of the casting and the 40 years of salt water but I have my doubts.  Anyway, he took off $100 on his charge so the total for cleaning and power-coating was $250.  I will post pictures soon.

In the meantime, I have a question.  What is the space I should allow between the lens-edge and the hatch edge?  The lenses I took out are not original and were not fabricated to high standards and were not even 1/4 inch thick.  I assume that at least 1/16 inch needs to be allowed for expansion but would like to know exactly since I need to make the templates and cut the new lenses.

I spoke with Bomar customer service and they said they would get back to me.  If I hear first, I will post again.

Fair Winds,

Chris

Dear All,

Bomar says that the gap between the edge of the lens and the edge of the hatch should be about 3/16 inches.  I hope to cut the cast acrylic this week and will post pictures when completed.

Chris

Dear All,

I have completed the lens replacement for my Bomar hatches.  And, yes, I made a mistake which I will share with you so you can avoid it.   I was careful to cut out the cast acrylic covering sheet at the places where it attaches to the frame and I did a pretty good job taping the frames.  I messed up by using too little building silicone for the support bars.  I am confident that the entire hatch will be waterproof and strong, the problem is aesthetic; you can see the silicone through the hatch lens and where it does not cover completely is unsightly.

The Professor offered a creative solution; use one syringe to apply more building silicone and one to allow the air to be released.  If I get enough courage to do this, I will post more pictures.

Fair Winds

Chris Mabel's Casse Tete 003/43 

Two more Pictures