Opening Ports installation in existing portlights

okawbow · Post by **okawbow** » Fri Apr 10, 2009 2:02 pm

Hi all, my first post on this board.

I recently bought 2 Beckson opening ports on closeout. I plan on installing them in my Bristol 24. The existing ports have plastic that is crazed and I planned on replacing them anyway. The new ports are slightly smaller than the existing plexiglass lights. Has anyone ever just installed ports in the plexiglass? If so, what tool did you use to cut the opening? I'm concerned that the plexiglass will crack if I try to saw an opening.

Thanks
Chuck
Bristol 24
"Harmony"

Post by **Tim** » Fri Apr 10, 2009 2:40 pm

Here's one guy's approach to installing new opening ports in old, larger openings. A bit unorthodox, but it worked for him. Maybe you can find at least part of an idea that clicks; maybe not.

okawbow · Post by **okawbow** » Fri Apr 10, 2009 2:58 pm

Thanks Tim,

Way more work than I had in mind. I think I can cut new holes in the existing plexiglass while it is still in place, and install the new opening ports without doing any more than sealing and bolting in. If I mess up, I,m not really hurting anything, as I need to change the ports anyway.

Post by **Tim** » Fri Apr 10, 2009 3:23 pm

Installing a new opening port within an existing plexiglass port (or deadlight?) doesn't sound like a very strong or attractive option, quite frankly, but maybe I am misunderstanding your intentions.

That said, it has been done before, with questionable results (as far as I'm concerned, anyway).

Quetzalsailor · Post by **Quetzalsailor** » Fri Apr 10, 2009 3:47 pm

I replaced the plexiglas ports in the Morgan 27. They were originally 1/4" grey-tinted and installed with flat head wood screws into the fiberglass. I replaced them with clear 1/4" and though-bolted with flathead machine screws and acorn nuts. Not a tough or expensive job; the issues were that 5200 is the wrong sealant for the application so it failed in a couple years, all the bolts had to be cut to length (the house top was not a uniform thickness) to suit the acorn nuts, and it was extremely easy to overtighten the bolts. That last, you don't discover until several months later when the plexi cracks from the wedging effect of the flat heads.

I think it would be a structurally bad idea to mount operable ports within the area of plexiglas ports, particularly existing ones with some age on them and which were not designed for the stress of holes cut in them. Plexiglas does become sun-damaged and the crazing you (might) see is a symptom; it becomes quite brittle. (The Morgan's 1/2" plexiglas forward hatch cracked in half when it dropped shut, after only 32 years service.)

okawbow · Post by **okawbow** » Fri Apr 10, 2009 5:23 pm

Tim wrote:Installing a new opening port within an existing plexiglass port (or deadlight?) doesn't sound like a very strong or attractive option, quite frankly, but maybe I am misunderstanding your intentions.

That said, it has been done before, with questionable results (as far as I'm concerned, anyway).

The new ports I have will nearly fill the space in the existing plexiglass. I would think they would add strength by removing most of the crazed plastic. If it doesn't work; I won't lose anything but a little time, and can always remove the ports and glass a solid filler in before re-installing the new ports. I'm wondering what tool works best cutting plexiglass.

Rachel · Post by **Rachel** » Fri Apr 10, 2009 5:31 pm

okawbow,

First of all, welcome to the forum!

okawbow wrote: If it doesn't work; I won't lose anything but a little time, and can always remove the ports and glass a solid filler in before re-installing the new ports. I'm wondering what tool works best cutting plexiglass.

Unless the failure occurs when a wave hits the cabin side, or you're heeled over and "window washing."

I don't mean to sound negative, and I have been guilty of perfectionism, but this just doesn't sound like a great idea to me. In addition to the crazing, I believe the B-24's ports are in metal frames, and oftentimes on these "built to a price" classics, the original frames did not have much (or consistent) overlap with the fiberglass of tghe cabin side to begin with. I'd want to get them out and see what I had, then do it right the first time on this critical, "keeps the water out" boat part.

Rachel

Post by **Tim** » Sat Apr 11, 2009 10:30 am

okawbow wrote:The new ports I have will nearly fill the space in the existing plexiglass. I would think they would add strength by removing most of the crazed plastic. If it doesn't work; I won't lose anything but a little time, and can always remove the ports and glass a solid filler in before re-installing the new ports. I'm wondering what tool works best cutting plexiglass.

Well, it's your boat, and you can proceed as you choose. But I can't suborn what I see as a poor idea with no merit and therefore won't spend any more time worrying about it. I think the responses you've received so far seem to point in a different direction than you're hoping.

No one is perfect and we all make mistakes, but to proceed knowingly down an unsuitable course really isn't what this forum is about.

Good luck.

okawbow · Post by **okawbow** » Sat Apr 11, 2009 2:04 pm

Tim wrote:
okawbow wrote:The new ports I have will nearly fill the space in the existing plexiglass. I would think they would add strength by removing most of the crazed plastic. If it doesn't work; I won't lose anything but a little time, and can always remove the ports and glass a solid filler in before re-installing the new ports. I'm wondering what tool works best cutting plexiglass.
Well, it's your boat, and you can proceed as you choose. But I can't suborn what I see as a poor idea with no merit and therefore won't spend any more time worrying about it. I think the responses you've received so far seem to point in a different direction than you're hoping.

No one is perfect and we all make mistakes, but to proceed knowingly down an unsuitable course really isn't what this forum is about.

Good luck.

I certainly have no problem with any of the responses to my post, and appreciate the advice. As far as my original question goes, however, I have heard of others doing the same installation, and Beckson also suggests it on their website as a viable installation. My boat is currently in the water, at a lake, and I like to sail as much as possible, so I saw a chance to get the cabin ventilation that my wife wants so badly, without a major re-fit. Before I take the boat out on an ocean passage again, I plan to replace all the ports with either new plexiglass or fill the old openings and install new ports. This will be a temporary, quick fix, and not a permanent solution to a hot cabin. I don't think it will sink my boat! So, cut me a little slack, and let's just see how it turns out. I guess I'll have to figure out how to cut the plexiglass on my own.

Oscar · Post by **Oscar** » Sat Apr 11, 2009 2:23 pm

This will be a temporary, quick fix, and not a permanent solution to a hot cabin. I don't think it will sink my boat! So, cut me a little slack, and let's just see how it turns out. I guess I'll have to figure out how to cut the plexiglass on my own.

I agree with you. My Catalina had a vent window in the head installed exactly as you describe, new out of the factory....look carefully on the rear of the port window.

If I were to do that I would get a new, best you can afford, sharp drill bit and drill along the outline on the corners and every two or three inches. Drill slowly.

Then I would take a dremmel tool and put new sharp zip bits in it and set it to slow speed and see what happens.

I have had good results cutting relatively thick fiberglass this way.

If it doesn't work well, get at least a half inch going along each of the four sides and then use a high quality, new, sharp hacksaw blade with one of these....go slow.

The reason you want to go slow, did I mention you need to go slow?, is that speed=heat=melt. You want to cut, not melt.

okawbow · Post by **okawbow** » Sat Apr 11, 2009 2:39 pm

Thanks!
I wondered about the zip bits. I have a dremel with a speed control, so maybe that's the way to go. I was also thinking about using a small battery powered circular saw for the long, straight cuts. It has a 4" thin, sharp blade. I'll try both on some scrap plexiglass first.

Oscar · Post by **Oscar** » Sat Apr 11, 2009 2:43 pm

a small battery powered circular saw for the long, straight cuts

Too fast. Cut, not melt. Try the scraps, you'll find out.

bcooke · Post by **bcooke** » Sat Apr 11, 2009 5:20 pm

I had a hard time using a saber saw with a fine tooth blade on some acrylic recently. I found it almost impossible to go slow enough not to heat up the plastic and have it melt itself back together behind the cut. Really really slow. A hand operated hacksaw might be the best approach.

I don't work with plexiglass enough but I know some plastics don't like using 'normal' twist drills either. The angle is too sharp and they tend to catch and crack the plastic. Low angle drill bits are often called for. But again, I don't work much with plexiglass in particular.

A Catalina used as a positive example on a classic plastic forum. What is the world coming too?...

Oscar · Post by **Oscar** » Sat Apr 11, 2009 5:24 pm

A Catalina used as a positive example on a classic plastic forum. What is the world coming too?...

Positive? ...nah, just that it can be done and is done.

With the exception of the 250 that I got new, my two other Catalina's were old, and needed tlc. The 42 was 20 years old when I sold it last year. Yes they are a mass produced boat, but structurally it held up nicely, and was a good sailing honest boat. Classic by every definition.

Rachel · Post by **Rachel** » Sun Apr 12, 2009 12:35 am

I'm sorry to repeat, as I know I've mentioned this here before, but I've found that an open forehatch with a Windscoop rigged will bring tons more air through the boat than opening ports will. There were ten opening ports on the boat I cruised on, and even all ten of them open didn't hold a candle to the Windscoop in the forehatch. So that might be a quick and easy option to try.

Here's what I'm referring to; it also gives you an idea just how effective they are at catching a breeze (and it doesn't have to be blowing a gale, either).

Looking aft:

Looking up from inside (v-berth):

One potential flaw in the above plan would be if you are at a dock and the breeze is coming across the beam (although even then you can rig the Windscoop to face the side; it's just not as "automatic" as it is at anchor or on a mooring where you nearly always face into the wind).

The volume of air, and the way it brings a hot muggy boat "to life," really is amazing. And only one thing to close when it starts to rain or you leave the boat.

Rachel

Hirilondë · Post by **Hirilondë** » Sun Apr 12, 2009 1:23 am

Rachel wrote: There were ten opening ports on the boat I cruised on, and even all ten of them open didn't hold a candle to the Windscoop in the forehatch.

With a wind scoop in operation holding lit candles is futile :)

All kidding aside, nothing comes close to a wind scoop for sleeping or hanging out comfort in warm weather. It doesn't take much wind to ventilate the whole boat when you set up a wind ram up forward and your companionway is wide open.

Zach · Post by **Zach** » Sun Apr 12, 2009 3:20 am

If you want to easily shape the plexiglass cutout... make a plywood blank of what you want it to end up looking like, and use a flush cut router bit to make the cut. It's worth the time...

Reciprocating saws (and band saws...) will work, but with acrylic (plexiglass is a brand-name...) you need a tool that throws a chip big enough that the heat from the cut goes with it... otherwise it melts to the saw, and if pushed to the limits melts back together behind the cut. Saws just fuzz it up...

If you want to cut it with a circular saw, or table saw... a hollow ground plastic cutting blade with loads of teeth will do the trick. On the real thin stuff though, its worth trying flipping the blade around backwards to see if the stupidly huge relief angle feeds smoother than trying to actually cut with the sharp side. (Yeah... wacky, but sometimes it works. Probably don't wanna try a carbide tipped blade... shrapnel!)

Britton is dead on that a low angle drill bit is nice to have for acrylic. You can use wood bits, but more often than not it'll crack a corner going through. Drill presses are nice, but you can hand hold it... use real light pressure to wear a hole through with fuzzy stringy stuff coming off... rather than trying to feed with any pressure, lest the bit catch and crack.

If you are hand holding, its almost better to leave the work free and when/if the bit grabs let the piece spin for a second. Calm down, lift the drill up for a second and start it again. Try to force it, and it'll crack.

Sometimes you can cheat cracks by putting masking tape or packing tape on both sides of the holes. Really though its nice to have a piece of scrap backed up tight under the hole so it blows out that piece, not the one you care about.

Make the holes oversized so that the plastic can expand and contract. Use bolts with a shoulder so the threads aren't stress risers. Do not chamfer the hole, as when the plastic expands it will act like a wedge. Washers and pan heads... or machine screws.

So... Make the form first, drill a mounting hole or two, undersized but on center... Mount the form to the window. Drill a hole big enough to slip in your flush cutting bit... zip around... and install the new window.

Router throws lots of chips, so tape up some plastic and cardboard (to keep the bit out of the plastic...) so your don't have a huge mess inside the boat.

(Way to late, but hope that makes sense...)

Zach - Former plastic dude... grin.

Zach · Post by **Zach** » Sun Apr 12, 2009 3:49 am

Oh... and if you must use a saber saw for a rough cut in a straight line... use the most fiendish looking blade you can find. Clamp down the part, with the blade as close to the edge of the bench as you can so it can't flex on the side you care about. Use a stock edge of another piece of plexi, or a piece of aluminum as a guide. Set the angle of the head (hopefully yours has an adjustment...) so it's taking as big a bite rather than straight up and down. Hold tight to the waste, just ahead of where you are cutting so it doesn't snap off at the end.

It'll make a hell of a racket, kick like a bronco, and isn't good for anything much thinner than a 3/16ths... but you can actually make a fast cut... The clamps make it happen without it cracking... just don't push on the saw, let it do the work and clear out the chip.

It won't be a clean cut, but it will push as far towards actually making a chip rather than fuzz that melts back together... the stuff works like butter once you are close anyway... Grab a big long smooth file and work it down the high spots and machining marks. Deburring tools are nice but not a requirement. If you care about the look, use your thumb nail or the back of a hacksaw blade... not your pocket knife.

A lot of guys try to use fine blades that are wide metal cutting ones... if you go for a scrolling blade has less contact to the sides of the cut, less friction... and easier cuts for the curves. You can get the specific acrylic cutting blades, but if you are making more than one of something... it's worth the time to jig it out and use a router.

You can try soapy water as a lubricant if it still wants to bog down... but in the machine shop I always used compressed air... mainly to blow the chips clear, so nothing rubbed the cutting tool and melted back to the part. Give it a try if you've got a compressor.

Go back and finish up to around 4-600 grit sandpaper, and follow up with a torch to go glass clear... if you care about flame polishing. (Flame polishing does add stress to the plastic, so it may not be worth doing for longevity sake...)

Zach - Can't sleep.

okawbow · Post by **okawbow** » Sun Apr 12, 2009 9:23 am

Rachel, thanks, I.m also making hatch screens on frames. We have a serious bug problem in the summer. I'll look into the Scoop, but my wife doesn't like too much air blowing on her, but can't stand it being "stuffy".

Zach, Oscar, I need to make the cut-out while the window is in the boat, so I need to use hand tools. My Craftsman battery powered circular saw did a great job cutting scrap plexi. Smooth cutting and no vibration. It has a sharp, carbide tipped blade with lots of relief. If all else fails, I have several small hand saws I use for violin making, and a dremel and router set. I'll grind a drill bit with a low cutting angle, for drilling the holes. I also have a carbide rotary file that works great on fiberglass, that I'll try to use for cleaning up the edges.

I'll post the results in a few days.

Zach · Post by **Zach** » Sun Apr 12, 2009 1:34 pm

I'm thinking the boat holding on to the window would be mighty nice... for power tools. Grin.

(But then again, whats an excuse to pull out something that is complete overkill...)

Oscar · Post by **Oscar** » Sun Apr 12, 2009 4:03 pm

On the real thin stuff though, its worth trying flipping the blade around backwards to see if the stupidly huge relief angle feeds smoother than trying to actually cut with the sharp side. (Yeah... wacky, but sometimes it works.

That's how we did vinyl siding in my one time construction second job....

okawbow · Post by **okawbow** » Sun Apr 26, 2009 2:57 pm

I removed one of my portlights, and after finding the plastic in worse condition than I originally thought, and upon finding the removal quick and easy; I bought enough 1/4" SparTech polycast super abraision resistant acrylic to replace all my portlights. I cut the plastic to size with a table saw and used a band saw to round the corners. I installed Beckson opening ports in 2 of the portlights, following the directions on the beckson website for installing ports in plastic portlights. I used 100% silicone as instructed for sealing. The resulting assembly actually feels stiffer and stronger than the plain portlights.

The tools used for cutting the plastic were: a hole saw for the corners, a battery powered cicular saw for the straight cuts. a recipricating saw for finishing the straight cuts, and a carbide rotary file for dressing the edges. I drilled the holes with a battery powered drill and metal working bits. The only problems with melting plastic were when using the holesaw. I found that short cuts and compressed air solved the problem.