Replacing lens on old Lewmar hatch

[vladkri]

Greetings,

How do I replace lens on this ancient Lewmar hatch? It seems I could remove the lid, bring home, take old glass out and have somebody cut the same. I guess first question how do I remove it? There is no model number anywhere and do not think there is any hope Lewmar has replacement.

Thanks

Top view


Hinge close up


Handle cap


Inside handle

[goboatingnow]

If it’s made since 2000 the model number is etched in the acrylic glass near the edge often under the rubber.

A replacement could be fabricated I suppose

[wingssail]

You will have to remove the hinges and the dogs. It may be difficult. Once the hardware is off you cut the sealant around the lens with a mat knife or carpet knife. You might have to cut from underneath also.

Once you have a section of the lens loose enough to pry up you may have success prying the whole lens loose. Otherwise more cutting is needed.

When the lens is out you can get a new one cut from similar plastic. I use acrylic. You can easily cut it to shape yourself with a jig saw and a blade with medium teeth. Watch that the plastic is not melting and clogging up the saw. Cut it with at least 3/16" to spare to allow room for sufficient sealant for expansion. Round the corners. Round all the edges slightly with a power sander.

For the holes for the hinges and the dogs make them slightly big so expansion won't cause them to bind and crack.

The frame needs to be carefully cleaned up, all old sealant removed. Some people recommend sanding the plastic where the sealant will touch it, to get better adhesion. I have not found that to make any difference.

Taping: Score the new lens with a mat knife so you can see what needs to be taped off underneath. On top side just tape it close to the edge. Tape the entire frame except where the sealant will be. I use blue masking tape.

Now gluing in the new lens: You may have trouble choosing a sealant which will stick to the plastic. Many people have recommended Dow 795. I've never been able to source that locally and shipping into Mexico is difficult. I've tried everything and had very mixed results. Even Sika 295 with primer applied does not work very well. I've had professionally installed plastic lenses simply pop off within a few months in the tropical heat (not good when it's your bow hatch and you are doing a rough crossing). 4200 or 4000 does not stick to Acrylic, I've not tried 5200 since Dow does not recommend it for plastic. A UV safe sealant is better. Recently I have tried "pens acetic silicon". It is not recommended for plastic either, but the plastic shop where I bought my acrylic, and which has hundreds of choices for sealants, recommended this product. Oh well. Be prepared for disappointment.

Installing: I apply a 1/4"-3/16" bead all the way around the frame then place the lens on it, gently. You don't want to squeeze out all the sealant. Then immediately shape it with a bare finger all the way around. Before it skins off you pull off the masking tape and hopefully it leaves a nice looking seal. Pulling off the masking tape from the underneath will be more difficult because often some tape will be caught between the frame and the lens where the hardware attaches.

Here is a weird "hack". Not too long ago my 31" square bow hatch came loose about 2 years after I put it on. The sealant was firm and stuck completely to the frame but not at all to the acrylic plastic lens on about 50% of the circumference. We were at sea and many miles from a port, and even then it was not near a city or town. Once choice was to drill through it and put bolts in. I didn't want to do that for looks mainly. What we tried, and which worked, was apply a layer of superglue on the old sealant then press down the lens onto the super glue. That has held. I am now tempted to use superglue as a primer.

[Franziska]

If you use Sika 295 UV to glue/seal make sure to add the required UV protection layer on the outside, as per their detailed instructions.

https://www.google.com/url?q=https:/...DcW39NAXbU-_a5

Can be tape or standart 2 component polyurethane paint in black.
Also use their black primer on the inside of the glass.

If neither or just one of them is used it will not last long. If you use both you have good chances of a long-term lasting glue joint.

[vladkri]

Thanks everyone. How do I remove the hinges? Just unscrew from the glass? Also, those caps over the handles, are they supposed to pop out?

[El Pinguino]

That hatch is circa mid early 1980s. Mine started leaking because people had been standing/stomping on them before I bought her. That is now a loggable/floggable offence.
I simply bought new Lewmar hatches which dropped straight in the same holes... fastener spacing was different.

[Rumrace]

There are several lens services. I admire your bravery. I hope you had better luck than I did same brand different model. Lens no problem seal never. Sent it in came back no leak.I’ve had the same problem reusing weather seal on old cars zero problem with new weather seal. Seems a one time deal.
I also have various replacement locks and handles if you need something reproduced

[jamhass]

I had great luck redoing my Lewmar hatches.

1. Carefully remove the old acrylic so you can use it as a template.
r3. Carefully and fully clean the frame.
4. Use the original carefully clamped to the new acrylic as a template and cut near to the line with a saber saw, use a blade designed for plastic.
5. Trim to the exact size with a router using a piloted flush trim bit.
6. Drill all existing holes. I STRONGLY advise using a drill bit designed for plastic, or modify regular bits (Google how). Also some holes may be odd sizes. Use the correct size bit. Over- or under-sized holes can lead to cracks.
7. I found that carefully sanding the areas where the sealant bonds does help.
8. I also used Sika and its primer.
9. Purchase some small plastic balls (1/16 inch). McMaster sells small plastic bearings. These serve as spacers to keep the Sika from extruding out of the joint while wet which can starve the areas and cause leaks. They can stay in place. Place them between the acrylic and the frame on all sides and "under" the acrylic.
10. Mask the area carefully.
11. Carefully apply the Sika to the frame, add the underside spacers, set the acrylic and Sika the periphery (don't forget the plastic balls.
12. Let it cure well.
13. Clean up,
14. have a beer.

[wholybee]

Originally Posted by wingssail

<snip>
Now gluing in the new lens: You may have trouble choosing a sealant which will stick to the plastic. Many people have recommended Dow 795. I've never been able to source that locally and shipping into Mexico is difficult. I've tried everything and had very mixed results. Even Sika 295 with primer applied does not work very well. I've had professionally installed plastic lenses simply pop off within a few months in the tropical heat (not good when it's your bow hatch and you are doing a rough crossing). 4200 or 4000 does not stick to Acrylic, I've not tried 5200 since Dow does not recommend it for plastic. A UV safe sealant is better. Recently I have tried "pens acetic silicon". It is not recommended for plastic either, but the plastic shop where I bought my acrylic, and which has hundreds of choices for sealants, recommended this product. Oh well. Be prepared for disappointment.
<snip>

Having tried all of those except "pens acetic silicon", I can vouch for Dow 795. Sika and the 3m products all failed, the Sika on my bow hatch during a long crossing. (butyl rubber kept it water tight until landfall-great stuff) Dow 795 is available on Amazon.mx and not expensive.

Once you get the acrylic out, I would take it to a local acrylic shop. Having them cut it to match the old one is a negligible cost when you are buying new acrylic. Even if you order new acrylic online, they should be able to cut it for you if you provide good drawings.

[ItDepends]

Another vote for Dow 795 or GE 2002. Basically the same product, and made for glueing windows in commercial buildings (think sky scrapers). If you do a good job either of these will be 100% successful at sealing your hatch for years.

Skip the standard "marine silicone" sealants, they are not made for this. They LOOK the same, but they are not.

Use acrylic NOT polycarbonate.

Also another vote to take the old lens to your local plastic shop and telling them to "Make me one of these." Yes, you CAN make it yourself, but life is too short for the minimal cost savings. They have all the tooling to do it quickly and cheaply. Working with plastic is NOT the same as working with wood, especially when it comes to drilling holes.

There is no reason to "expect disappointment." This is a straightforward project. If done with care and attention to detail you will be successful.

[geoleo]

Better send to Hatchmasters in MA

[double u]

on some of these old models (Superhatch)you have to drive the hinge pins out to remove the lid, destroying plastic parts of the hinge that have to be raplaced with hinge kits,-very rare today

[double u]

might be https://hatchmasters.com/product/lew...tch-hinge-kit/
https://selectplastics.com/140/

[double u]

Superhatch 1 (now Sz 30) 376 x 506 14,8 x 19,92 Hinge Kit 361002999
Superhatch 2 (now Sz 50) 426 x 556 16,77 x 21,89 Hinge Kit 361003999
Superhatch 3 (now Sz 60) 566 x 556 22,28 x 21,89 Hinge Kit 361004999
Superhatch 4 (now Sz 70) 676 x 676 26,61 x 26,61 Hinge Kit 361005999
Superhatch 5 (now Sz 40) 476 x 476 18,74 x 18,74 Hinge Kit 361005999

try to find the part numbers, some dealers might have leftovers

[bensolomon]

Originally Posted by wingssail

You will have to remove the hinges and the dogs. It may be difficult. Once the hardware is off you cut the sealant around the lens with a mat knife or carpet knife. You might have to cut from underneath also.

Once you have a section of the lens loose enough to pry up you may have success prying the whole lens loose. Otherwise more cutting is needed.

When the lens is out you can get a new one cut from similar plastic. I use acrylic. You can easily cut it to shape yourself with a jig saw and a blade with medium teeth. Watch that the plastic is not melting and clogging up the saw. Cut it with at least 3/16" to spare to allow room for sufficient sealant for expansion. Round the corners. Round all the edges slightly with a power sander.

For the holes for the hinges and the dogs make them slightly big so expansion won't cause them to bind and crack.

The frame needs to be carefully cleaned up, all old sealant removed. Some people recommend sanding the plastic where the sealant will touch it, to get better adhesion. I have not found that to make any difference.

Taping: Score the new lens with a mat knife so you can see what needs to be taped off underneath. On top side just tape it close to the edge. Tape the entire frame except where the sealant will be. I use blue masking tape.

Now gluing in the new lens: You may have trouble choosing a sealant which will stick to the plastic. Many people have recommended Dow 795. I've never been able to source that locally and shipping into Mexico is difficult. I've tried everything and had very mixed results. Even Sika 295 with primer applied does not work very well. I've had professionally installed plastic lenses simply pop off within a few months in the tropical heat (not good when it's your bow hatch and you are doing a rough crossing). 4200 or 4000 does not stick to Acrylic, I've not tried 5200 since Dow does not recommend it for plastic. A UV safe sealant is better. Recently I have tried "pens acetic silicon". It is not recommended for plastic either, but the plastic shop where I bought my acrylic, and which has hundreds of choices for sealants, recommended this product. Oh well. Be prepared for disappointment.

Installing: I apply a 1/4"-3/16" bead all the way around the frame then place the lens on it, gently. You don't want to squeeze out all the sealant. Then immediately shape it with a bare finger all the way around. Before it skins off you pull off the masking tape and hopefully it leaves a nice looking seal. Pulling off the masking tape from the underneath will be more difficult because often some tape will be caught between the frame and the lens where the hardware attaches.

Here is a weird "hack". Not too long ago my 31" square bow hatch came loose about 2 years after I put it on. The sealant was firm and stuck completely to the frame but not at all to the acrylic plastic lens on about 50% of the circumference. We were at sea and many miles from a port, and even then it was not near a city or town. Once choice was to drill through it and put bolts in. I didn't want to do that for looks mainly. What we tried, and which worked, was apply a layer of superglue on the old sealant then press down the lens onto the super glue. That has held. I am now tempted to use superglue as a primer.

This was a great post!! Thank you!