Working with Lexan

bcooke · Post by **bcooke** » Sun Sep 16, 2007 9:28 pm

Looking ahead to when my deck and coachroof is painted, I need to get some new deadlights made.

I was going to use Lexan and was just wondering what sort of tools are used when working with it. Can I just use a fine toothed wood saw, wood drill bits, and normal router bits or do I need to be a bit more careful?

-Britton

deckhand · Post by **deckhand** » Sun Sep 16, 2007 10:35 pm

basically, wood working blades for circular types of saws will work as long as they are carbide toothed and you go slow. However, if you want the cleanest straight cuts you should get a plastic/laminates blade. Most carbide teeth look like this || while every other tooth on a plastic blade will
look more like this / \
Basically it clears out the cut so that the hot plastic doesn't fuse.
For reciprocating blades, get a blade made for plastic and make sure you either go slow and steady on the cut or even better, use a variable speed scroll/jig/bandsaw. For bandsaws you don't need another blade.
For routers, just make sure they are carbide and of course, go slow. The whole go slow thing isn't so that you slip or something, its so you don't heat up the plastic, ruin the part and kill your blade.
For drilling, make sure the blades are sharp as can be (a dull one will only melt and crack the lexan/polycarb) and let the blade do the cutting. Do not use forstner bits if you can help it. Thats about it, hope that helps.

CharlieJ · Post by **CharlieJ** » Mon Sep 17, 2007 1:50 pm

Actually, lexan is pretty much a piece of cake to work. Most any saw will cut it, most any drill will drill it. It's easy to use. PLEXIGLASS is tougher.

The reason is that Lexan is much softer than plexi, so doesn't have the same tendency to crack. But keep it flat while cutting.

I've successfully cut it with portable jig saws, with whatever blade was in there, band saws, table saws, cut off saws, what ever. Not a problem, but the finer the teeth, the smoother the cuts will be. Within reason- too fine a blade will melt it- too slow will melt it, tooo fast will melt it. But it'll only take you a couple of minutes to learn how fast.

You can rout it with carbide bits also and sand it with power sanders- edges, etc

When you are drilling, be SURE to oversize the hole slightly for the screws you'll use. and DON'T countersink those screws or use flat head screws- those countersinks will act like little wedges and eventually crack the edges outside the screws- use pan heads instead. If you MUST sink them, bore a shallow hole with a forstner bit just larger than the screw head- but still use pan heads. Bore the shallow depression first, then centerbore your screw hole.

Of course larger forstner bits should be used in a drill press- but they'll cut lexan like drilling butter.

Jason K · Post by **Jason K** » Mon Sep 17, 2007 2:38 pm

I've used lexan for the hatches on the J/30 and the portlights on the Triton. On the longer, straighter sections, the lexan cut easily with a circular saw. I cut the corners with a jigsaw and sanded the cut edges smooth.

It is really pretty workable - easier than HDPE (starboard) and about the same as G-10 FRP sheets.

bcooke · Post by **bcooke** » Tue Sep 18, 2007 2:29 pm

Great info. Thanks.

-Britton

bcooke · Post by **bcooke** » Fri Oct 05, 2007 1:50 pm

I guess the most important question that I forgot to ask was,

"Anyone got a good source for lexan stock?

-Britton

Jason K · Post by **Jason K** » Fri Oct 05, 2007 1:59 pm

I buy mine from a local glass store. They are often sold in rather large sheets so, unless you're buying a small, pre-cut piece, you'll lose any savings to the extra shipping costs.

jollyboat · Post by **jollyboat** » Sat Oct 13, 2007 8:31 pm

Britton,
Ebay

triton318 · Post by **triton318** » Fri Oct 19, 2007 9:50 am

Does anyone else buy from McMaster-Carr? (http://www.mcmaster.com/) I've purchased quite a few items from them over the years, and have always been satisfied with the prices. They ship fast, too. I've purchased Lexan, bronze rod, stainless, rubber, etc. If you've never been to their site, you should check them out sometime.

Hirilondë · Post by **Hirilondë** » Fri Oct 19, 2007 5:08 pm

Buying polycarbonate commercially vs retail makes buying from McMaster Carr probably two different comparisons. If you are buying partial sheets (less than a 4'x8',4'x-10') then it is probably a fair and reasonable price. Commercially we can do considerably better using regional wholesalers. You can try your local glass shop and see what they will do for you. The mark up on this stuff is high. Some places will give you a break.

Bluenose · Post by **Bluenose** » Fri Oct 19, 2007 7:47 pm

This is probably a bit off topic but has anyone used automotive safety class for their deadlights? I boat builder friend had some specially cut for a job he was doing and it seemed like a neat idea.

Post by **Tim** » Sat Oct 20, 2007 6:33 am

It's been used many times, on many boats, and is a good possible choice.

JonnyBoats · Post by **JonnyBoats** » Sat Oct 20, 2007 9:35 am

automotive safety class for their deadlights

Bill Seifert in his book recommends

monolithic tempered safety glass, minimum 1/2 inch thick

as a longer lasting alternative to Lexan.

Is automotive safety glass available 1/2 inch thick?

Rachel · Post by **Rachel** » Sat Oct 20, 2007 11:43 pm

Edited to say: Well, as I think about it, maybe 1/2" isn't that thick, but for what it's worth, I'll leave my original comments below.

*****************

Wow, that sounds really thick, doesn't it. I wonder how he got to that figure? Are there guidelines for commercial vessels that give that sort of thing?

My brother had a BMW 750 a few years ago that had some kind of "security package" (he didn't buy it new) that included "bulletproof" windows. When you rolled down the door windows, it was amazingly thick. I wouldn't be surprised if it was 1/2". Not sure what type of glass it was though (safety, tempered, laminated), or what the difference is between those (if there is one).

Say, Charlie, did you happen to measure the thickness of the glass in your Meridian when you had it out?

As I think about it further, I wonder how "storm proof" the glass needs to be, because if you were going offshore, wouldn't you still want storm shutters -- on account of the fact that there isn't that much frame strength/overlap on most large fixed ports? No sense making the glass five times stronger than the frame... (I'm thinking of the classic '60s style like on Tritons, etc.)

JonnyBoats · Post by **JonnyBoats** » Sun Oct 21, 2007 5:29 am

I wonder how "storm proof" the glass needs to be

Bill Seifert goes on to say:

If safety glass is used, the design of storm shutters should allow them to be bedded as replacement windows in the event the window glass is fractured.

As to thickness, he also recommends 1/2 inch for Lexan as well.

Rachel · Post by **Rachel** » Sun Oct 21, 2007 10:40 am

Thanks for that additional info.

The fact that it's Bill Seifert doing the recommending just sank into my head; he's pretty sharp, and I'd generally give his advice a lot of credit.

R.

Zach · Post by **Zach** » Sun Oct 21, 2007 8:22 pm

I don't mean to divert the course of this thread... but how would you guys and gals go about reinforcing the window frames, and cabin top?

I haven't done any exploratory drilling to see if the cabin top is cored around the windows, or solid. The idea of replacing the fixed ports for opening ones interests me, even though it drastically changes the lines of the triton... extra ventilation! (Perhaps they are less strong as well...)

The aft sides of the cabin on either side of the companionway are easily flexed with hand force, as is the top on either side of the sliding hatch.

bcooke · Post by **bcooke** » Sun Oct 21, 2007 8:41 pm

In every Triton I know of, the top of the doghouse is cored. The sides are not.

I have heard the arguments for ventilation before but I haven't found my Triton to be particularly 'stuffy' and requiring extra ventilation. Most of the times the boat will be pointing into a breeze so the forehatch and front opening ports will keep it well ventilated. On those occasions when the breeze is on the beam you still have two ports each side that open. Replacing the big 'picture window' side windows would mean giving up a lot of light and a pretty view. I guess it would depend on your own personal preferences.

how would you guys and gals go about reinforcing the window frames, and cabin top?

The frames (in my case aluminum) are relatively flimsy and only overlap the cabin sides by 3/8" around the edges. I think if I wanted beefier side lights I would just bolt on a wider piece of Lexan over outside of the holes. It is hard to make that look good though.

As for the cabin top. If the coring is good and the bond between the coring and the fiberglass skins is good then the the cabin top should be plenty stiff by itself. I can jump up and down on mine with no deflection If it is deflecting down with hand pressure then you probably have something going wrong there.

That Ebay suggestion was good. Brian There is a lot of end pieces for sale - mostly 12"x12" and the like.

-Britton

Rachel · Post by **Rachel** » Sun Oct 21, 2007 9:35 pm

Say Zach, when you say the cabin is deflecting, do you mean the molded fiberglass liner on the inside (in mid- to later boats)? I could imagine that flexing without meaning trouble (although I defer to actual Triton owners for the last word, of course).

Zach · Post by **Zach** » Sun Oct 21, 2007 10:47 pm

Mine is an early year, so no inner liner... just the bottom skin of the deck.

If you push/pull on the sides of the companion way, it deflects. Not a whole, but enough that I'd like to reinforce it. The cabin top is strong, and doesn't feel wimpy under foot... nor did it break when I pulled the engine out with a 2x12 across the top.

It just deflects... and my farm boy ingenuity says that stuff that flexes breaks. I'm wanting to glass half of a cardboard tube around the top inside, and down the edges of the companionway. (If I leave a piece of wire inside, I'll pull the wires that feed the side marker lights through this!)

The companionways wood trim is a bit beat up/broken on mine, I'm pondering replacing the U-channel with stainless steel, and just trimming it in wood for show. Only the hatch boards can expand and contract enough to matter... so they ought to be made to fit tighter to ship less water. (Plus I can make metal grow back if I cut it small... grin!)

I'd like to replace the the wooden rails that hold the metal slider, and build some laminated ones and epoxy them in. Mine have seen better days...

Lastly, if I can find the bucks for another bottle of gas and 316 wire for my MIG, I'm going to fabricate a stainless handrail for the cabin top, to replace the aging... spindly ones she's got. (Not looking forward to polishing these, but they haunt my dreams.)

Post by **Tim** » Mon Oct 22, 2007 6:29 am

Zach wrote:...stuff that flexes breaks...

Ever been on a bridge...or in a tall building?

More accurately, one should perhaps say that "stuff that isn't supposed to flex, but does repeatedly, breaks". Stuff that is naturally designed to flex is actually very strong--like the steel in a bridge, or the solid fiberglass parts of most boats. Obviously there are limits in all these cases.

Seriously, though, I know what you're saying about the aft bulkhead around the companionway opening. That's a solid fiberglass laminate of only about 3/16" max in thickness, and it absolutely does flex if you yank and pull on it. That large opening in the middle (the companionway, that is) also takes away a lot of the strength and rigidity this bulkhead would otherwise have.

The long and the short of it is that if you feel a need to reinforce it to make yourself feel better about it, then by all means do so. Further justifying this by making it double as a wire chase is a fine idea if you choose.

In practice, this area doesn't flex under normal use. The only scenario in which the general lack of beef in this particular area might be cause for legitimate concern is if you were theoretically taking large boarding seas over the stern that directly impacted the aft bulkhead. Frankly, though, the companionway hatch itself is the weak link in this chain and seems to me as if it would act as a sort of safety valve--the companionway boards would break first, thereby saving damage to the fiberglass. (Consider this when contemplating whether to reinforce the companionway or not.)

We're talking an extreme (and extremely unlikely) scenario here. At some point, everyone has to accept the natural limitations (and associated minimal risks) of the boats they choose for whatever pursuit. One can dream up doomsday scenarios all day long, and generally find weaknesses in any structure. Nothing you or anyone else can do will guarantee absolute structural integrity and safety against the will of Mother Nature and the seas.

You're better off preparing yourself for what might happen were you to go offshore than worrying too much about trying to reinforce parts of an otherwise sound boat. Most boats that are abandoned by a frightened crew end up surviving the storm just fine, to reappear ashore or drifting calmly weeks after the event. Much poorer boats than most Tritons have survived worse than your boat is ever likely to face.

The flexing of this bulkhead alone is not a general cause for concern. It's the nature of the beast. Keep in mind that reinforcing one area naturally makes it stronger (duh), which in turn can have an affect on how an adjacent area might react in a stressed situation.

Repeated oilcanning of a fiberglass laminate can and does cause delamination over time. However, this is not happening to your bulkhead, unless you keep shaking it yourself every time you go through. The flex means that it's relatively thin and lacks backing stiffeners, but that doesn't mean it's going to break either. What's moving when you see this motion is the whole panel, not one section of the panel within itself. There's a difference in terms of how this translates to the ultimate strength and damage resistance of the panel.

Every part of your boat (and every boat) flexes in ways you'd probably rather not think about. It's just how they are. Fiberglass is strong and flexible, within normal limits.

Just some practical throughts.

Zach · Post by **Zach** » Wed Oct 24, 2007 12:30 pm

Thanks Tim.

I go a bit wild at times... (Grin)

Zach

westsail42 · Post by **westsail42** » Thu Oct 25, 2007 9:46 am

We are avoiding Lexan on our 28 footer this time around. The coating tends to fail after a few years. Looks ugly. Especially after repeated taping for varnish.

New portlights will be tempered glass.

keelbolts · Post by **keelbolts** » Thu Oct 25, 2007 2:52 pm

I'd say it's all but impossible to build a boat that will stand up to anything the sea can throw at you. Pick a good boat, take reasonable precautions, take the right safety gear (series drogue, sea anchor, etc.), choose a good weather window, say a prayer, and go. The Smeetons, in a 50-some foot boat were pitchpoled by a single rogue wave. I think history shows, with few exceptions, that survival is more about knowledge and good luck than it is about thicker fiberglass. Most of us fight with that history because we don't like admitting that we're not in control. Sometimes your butt is just hanging out there and there's nothing you can do about it. That old line about a sailor leaving as an atheist and returning a believer was no doubt coined by a sailor.

Summersdawn · Post by **Summersdawn** » Thu Oct 25, 2007 6:03 pm

keelbolts wrote:The Smeetons, in a 50-some foot boat were pitchpoled by a single rogue wave. ...

I believe that was twice.

Tzu Hang

jollyboat · Post by **jollyboat** » Fri Oct 26, 2007 9:23 am

Britton - glad to hear the ebay suggestion was found to be usefull. In rebuilding the forward hatch I wanted to use the white Lexan and found that my local Select Plastics store wanted my arm and my leg in return - I found a nice piece of white Lexan for a very reasonble (fair) price on ebay.

CharlieJ · Post by **CharlieJ** » Sat Oct 27, 2007 9:19 am

Yes- the Smeetons were pitchpoled twice trying to round the horn. John Guzzwell was aboard the first time, and has an interview logged on Furled Sails, where he discusses that first time.

I don't know the link- my wife found it and has it on another computer but try googling "FurledSails"

Zach · Post by **Zach** » Sun Oct 28, 2007 6:16 pm

Furled Sails: http://www.furledsails.com/article.php3?article=736

Zach · Post by **Zach** » Mon Oct 29, 2007 6:36 pm

I just finished listening to it... strangely enough, the Smeetons lost their dog house when they were pitch poled!

Zach · Post by **Zach** » Tue Oct 30, 2007 3:29 pm

Came across this article:

http://www.boatus.com/goodoldboat/bronze.asp

Alberg 30 with the non-opening lights swapped for ones that open.

Zach

bcooke · Post by **bcooke** » Tue Oct 30, 2007 4:23 pm

Since 2001 when the article was written the price of bronze has gone up considerably. Using one of their links in the article an 8x18 bronze opening portlight was listing for $525.

Times 4 makes for an expensive upgrade. There would also be considerable work filling in the old holes too.

Do-able but not for the faint hearted. I guess you would have to ask yourself if it was really worth it to you. That time and money could perhaps be better spent on other important projects.

A couple of years ago I floated the idea of just bolting plywood along the cabinsides before a passage. When you arrive on the other side, take the plywood off and toss it in the dumpster. For the 1% of the time that most cruisers are actually in blue water this seemed like a more economical alternative to me. Or try it for a bit and if you find you really want the upgrade then by all means do it. Most people find out though that they don't spend nearly as much time in deep water as they first expect.

Your mileage may vary.

In my case, I like the idea of beefing up the port structure. It is how to do it aesthetically and practically that has me stumped. And really the ports are only one of many 'weak' points in these old boats. It really doesn't help to have bullet proof windows only to have another 'weak' link sink you. Few of these boats were built for blue water cruising and the fact that they do is more credit to the design than overall strength or workmanship. Luck may also play a bit of a factor. With a little luck any boat can cross an ocean. (there are plenty of ill-conceived attempts that have made it- check your local library) Conversely, with a little bad luck, any boat can be lost.

Tritons, A30's etc. were built for coastal cruising. In that regard they excel (if you can forgive the lack of living space). They can cross oceans but that is definitely not what C. Alberg/T.Potter/the Pearson cousins or the boys of Whitby had in mind when they created these boats.

strangely enough, the Smeetons lost their dog house when they were pitch poled

Actually, this is a typical point of failure on boats of that classic design. Those hard right angles supporting wide flat surfaces are the weak points when slapped with a few tons of wave action.

-Britton

bcooke · Post by **bcooke** » Tue Oct 30, 2007 4:40 pm

Rachel wrote:As I think about it further, I wonder how "storm proof" the glass needs to be,

Exactly. The window itself is only held in by a 3/8" lip. That wouldn't survive much of an impact. One could bolt on wider windows on the outside leaving maybe an inch border all the way around but getting that to look decent would be tricky. That still only leaves (1"x circumfrence of port) inches of fiberglass taking the impact load of a wave or a broach. The fiberglass on the cabin sides of the Triton is what?... 0.125-0.185 inches thick? How much of an impact is that really going to withstand?

Real storm shutters would take most of the force of the impact and spread it across nearly the whole of the cabin side. Still not real comforting but a vast improvement over the current setup.

Boats designed for blue water have small ports for a very good reason.

Tristan Jones advocated no ports at all. He figured when you were out at sea why the hell would you want to look out the window and see more of it?

And yes, I have worked on a BMW 750 (a nightmare if you ask me). So many were sold to private security firms that for a while they were only produced with 'bullet proof' glass - 1/2" thick.

-Britton

Figment · Post by **Figment** » Tue Oct 30, 2007 8:56 pm

Buncha friggin opinionated know-it-all punks on this forum.

bcooke · Post by **bcooke** » Tue Oct 30, 2007 10:50 pm

You don't know what you are talking about Mike. Listen to me. I have it all figured out.

-Britton

bcooke · Post by **bcooke** » Wed Oct 31, 2007 3:19 pm

Speaking of opinions...

I should have thought of this before. If there is one person that has an inkling about Tritons and blue water it would be James Baldwin on Atom. After two circumnavigations on a Triton I think he has an opinion I would take to heart.

If I remember correctly, he replaced the plexiglass with lexan and custom made some frames. James checks in here once in a while but he has also been kind enough to answer some of my questions when I emailed him directly.

I think Rachel has visited Atom so maybe she can recall how James dealt with his big windows.

-Britton

Rachel · Post by **Rachel** » Wed Oct 31, 2007 5:53 pm

Britton,

I think James talks about it on his website, www.atomvoyages.com

As I recollect he re-used the frames but installed thicker Lexan and ... perhaps through bolted? Before that he used plywood shutters.

There are a few "project" pages and some project photo pages on the site that I believe have text also. I'm on my way out the door, or I'd look first and then sound less vague.

R.

CharlieJ · Post by **CharlieJ** » Sun Nov 04, 2007 10:55 am

I just happened to read an idea last night on this. Fellow cut oversized plywood shutters, with a seal around the edge and used a single bolt through a wooden cross toggle. He put two toggles on each shutter.

These were stowed below, under the forepeak cushions. (minus the bolts) Should a port be knocked out, he could stick the shutter through from inside the boat, twist the toggles and tighten a wing nut to hold it in place.

Not a perfect solution, but workable for an occasional trip across the blue stuff.

Rachel · Post by **Rachel** » Sun Nov 04, 2007 11:11 am

I guess I'd better keep on sipping my coffee. I read the first sentence of your post, Charlie, and spent a good ten seconds thinking "Single bolt and toggle.... he drills a hole through the port or cabin-side to mount it?"

Of course the second half of your post made it all clear.

Sip, sip.

Rachel