V Berth Hatch Window

[twodzusfittings]

I decided that the original lens had way too much crazing and needed to be replaced. So I took some one sided sticky clear plastic sheet and copied the old existing lens while it is still in place. Then I transferred it to a piece of left over smoked plexiglass glass. Cut in with a very fine tooth band saw blade, sanded it and finished it with a 1/4 round on the router. Final sanding was done with a scotchbrite scrubber to make it a smooth finish but rough enough to let Dow 295 adhere to it. Now it's waiting for the day to be installed.

 

[kappykaplan]

Nicely done!

 

[Ralph Johnstone]

Final sanding was done with a scotchbrite scrubber to make it a smooth finish but rough enough to let Dow 295 adhere to it.

Or is that DC 795 ?

 

[twodzusfittings]

Or is that DC 795 ?

yup that!

 

[Richard19068]

I did similar on my O'Day 31. My issue was that the hatch is slightly rounded so the lens needs to have a radius to fit properly.
Is your hatch opening flat?

 

[twodzusfittings]

Is your hatch opening flat?

No. It will be heat bent slightly. I will create a wood en bending cradle that will have the curve I need and once all is strapped in and ready, I will apply heat and continue to bend by pulling on the straps. Heat will be generated by my halogen floor mounted work shop light. It's minimal but should be done. Once it's sat in the curve for a while, Im going to put it in the snow (if we get any) to cool off. Then leave it in the cradle until it's time to install. I took the lens down to the boat today. I need to sand off about 1/32" left side on the curve. Otherwise a very neat fit.

 

[Richard19068]

No. It will be heat bent slightly. I will create a wooden bending cradle that will have the curve I need and once all is strapped in and ready, I will apply heat and continue to bend by pulling on the straps. Heat will be generated by my halogen floor mounted work shop light. It's minimal but should be done. Once it's sat in the curve for a while, Im going to put it in the snow (if we get any) to cool off. Then leave it in the cradle until it's time to install. I took the lens down to the boat today. I need to sand off about 1/32" left side on the curve. Otherwise a very neat fit.

Okay. Same as mine. I put the radius in with a similar jig, but no snow here. I had the hatch cover at home and used some clamps to make sure the bow stayed in while the adhesive (BoatLife Life Seal) dried. It's been good for 15 years or so so far.

 

[twodzusfittings]

So my bending contraption did not work. Way too much time spent on trying to make a perfect clamp. Gave it the old "British" way. So far it's worked.

 

[Ralph Johnstone]

Gave it the old "British" way. So far it's worked.

"British way" ? ? ? How's that ?

 

[dlochner]

So my bending contraption did not work. Way too much time spent on trying to make a perfect clamp. Gave it the old "British" way. So far it's worked.

Just bending won't work. It has to be in an oven at a specific temperature and time.

 

[twodzusfittings]

Just bending won't work. It has to be in an oven at a specific temperature and time.

And what is the specific temperature and time, may I ask?
I'm not without common sense. I spent 30 minutes with a heat gun slowly heating it up and incrementally increasing the tension on the strap.

 

[twodzusfittings]

"British way" ? ? ? How's that ?

Not over complicating it!

 

[dlochner]

And what is the specific temperature and time, may I ask?
I'm not without common sense. I spent 30 minutes with a heat gun slowly heating it up and incrementally increasing the tension on the strap.

There are plenty of links in simple search that will give you guidance. From the couple I looked at it appears the acrylic needs to be heated while flat to the point where it is quite flexible and then put in the mold, somewhere around 250° F.

 

[twodzusfittings]

I used a "Bendomatic" plexiglass shaping tool. An excellent tool. Brought the plexiglass surface temperature to 245 F, let it sit for 12.23 minutes at that temperature, adjusted the bend setting to an additional 5.333 Ilbs per sq ft, let it cool to 24F with a wind chill factor to make it feel like 17F and I think we have enough curvature to let it sit nicely into the opening of the hatch cover. I'll use VHB tape and Dow 795

Just messing with you......

 

[Richard19068]

Is that really 12.23 minutes or do you mean 2 minutes 23 seconds??

 

[Ralph Johnstone]

let it sit for 12.23 minutes

I can see the need for the extra 0.23 min. (13.8 sec.) over and above the original 12 min.

However, I do think that using air with a wind chill factor of exactly 17° F is stretching it a bit too far for cooling the acrylic .

 

[twodzusfittings]

I am so disappointed with you all! Nobody commented on the fact that Newton (fig) foot pounds measurement was incorrect! What kind of critics are you?

 

[Ralph Johnstone]

Newton (fig) foot pounds measurement

All I ever saw anywhere near that fancy unit was :

adjusted the bend setting to an additional 5.333 Ilbs per sq ft,

.................... which is a unit of pressure.

You 'cusin' me o' bein' both deaf as well as blind in one eye and can't see outa the other ?

Harummmmmph !