Can someone talk me off the ledge?

[NevisDog]

You realise that if you take a long piece of timber and try to bend it by pulling in the middle, it will break in the middle. You have to ease it out all along its length, or is that too obvious?

[Tatheelrod22]

This is all so new to me. If I took them in height from the current (and original) 2.5" to saw 1.5", and the proportions looked okay think that change would lessen the stress?

[Tatheelrod22]

First, never assume something is too obvious with me. I've earned it. But you are correct with that and I realized that however since the wood had already been to that position before when clamped to the old rail template. I would have thought it would be okay. Heck, I wasn't even really attaching, just testing.

[NevisDog]

Teak is valuable timber - shame to break it in an experiment.
How about reverting to cheap, straight-grained lumber for these trials and see how easy/hard it is to bend to shape and/or see how it looks with reduced dimensions? Then it won't matter how many pieces get broken, at least until you've found something that may work. Steaming or laminating would be my choice (though I haven't steamed or laminated teak). Steamed or laminated timbers require a jig to clamp it around, with a tighter radius than the finished bend. Screw down the clamps evenly and slowly if steamed, but not so slow it has a chance to cool. Darn - it takes practice maybe, so don't waste all of your good teak.

[Kita]

I am no expert with wood, but I can tell you with patience and some moisture and if you really lucky to have the equipment some steam wood will bend amazingly well. I never had the benefit of being able to use Steam but what I did use was time and water in a little bit of a jig that I built so I can bend it a little bit every day I would get a little water on it and let it sit in the Sun in The Jig and bend it a little bit more everyday, & it kinda is a judgment call on how much but you need to go a little more than the original piece because it's going to spring back.. I was using cement blocks & whatever I could find for the jig,wet it good repeatedly and then put a little weight wherever you want to bend it and then support it properly and be patient. I was in no hurry with what I was working on and I could always go back to it and tweak it a little bit while I was doing something else but if you're in a hurry I would think Steam, but like I said I am no expert at this at all that was just a method that I used. I am sure there are many other folks here that have better information

[Tatheelrod22]

It's interesting in that I think the opinions on whether or not steaming teak will work seem to be about 50/50. Before I started this process, I bought a steam producer, so all I suppose I would need to do is but a long piece of properly sized PVC, rig it up and steam away!

I think take your suggestion and use some less expensive wood to see if shorter looks decent. The more I look at it the more I think they are pretty tall, thus a bit shorter wouldn't be an issue.

[jimbunyard]

'One doesn't steam teak' is a gray area statement, that would be more properly put as 'teak doesn't respond as well to steaming as do some other species'.

Steaming can work with teak (though I've never done it), but the guidelines you'll find online are important.

1. An hour per inch of thickness at full 212 temp steam.

2. Plan the process very thoroughly, have a strong, secure mold to clamp the piece to straightaway from the steambox, speed is essential; get the initial bend done right off, then come back and clamp the center sections to the mold. If it takes more that a minute to clamp, that's too long.

3. There will be springback, so set up your mold for a bit more curvature than you want in the finished piece.

4. Kiln-dried lumber is less amenable to the process than air-dried lumber.

[TrentePieds]

The sketch I promised Tatheel appears to attach to this email when I ask my machine to do so. So this is a test. If the sketch doesn't show, I'll have to have a serious talk with the scanner.

TP

[TrentePieds]

lessee if this did it then.

TP

[mike d.]

Yes ! I you cut down the height of the teak rail it will lessen the resistance to the compound curve you are trying to get! I do think you need a larger self tapping screw, or as TrentePieds shows above a wood screw would work as long as you have the depth under the deck for the screw to get a good bite !

[TrentePieds]

Okay, that's better :-)

Now back to bending! I think it is important that the ASPECT RATIO of the rail X-section should be about as shown in my sketch, which is basically where you started. The rail has to be substantially higher than it is wide in order to prevent it capsizing and twisting as you put the bend - the horizontal one - in it.

The hull/deck joint confines you to screws, rather than bolts, for the fastening. Furthermore, given the flimsiness of the joint, screws of lesser gauge than #12 are not likely to have enough holding power because the thread area will be too little, and the screws will simply tear the fibreglass lay-up. Only that part of each screw that goes through a part of the moulding where there are actual filaments of fibre will have effect. Any part of the screw that is in a part of the joint that may consist of "goop", resin with "microballoons" for example, will have no holding power to speak of.

Now we are back to some design considerations that arise from the nature of the wood used. Teak's principal characteristic is not that it is "hard" or that it is "soft". It has poor abrasion resistance, which is why cabin soles are splined with holly (holly has great abrasion resistance). Teak cuts easily and cleanly AS LONG AS YOUR TOOLS ARE SHARP! Which they won't be for long due to the quantity of chitin , an abrasive, contained in the wood. What teak REALLY is, is BRITTLE, as opposed to "tough" like e.g. hickory.


We already know that a #12 screw requires a 7/32” clearance hole, and a #14 requires a 1/4” clearance hole. Let's say we choose a #14 which is obviously better than a #12 because it has more thread area. Then on each side of the hole we need “goods” to the thickness of twice the diameter of the hole. In consequence, the thickness of the material, in this case the width of the rail, must be five diameters, i.e. 5/4”. That happens to be the thickness of the “raw” plank as it comes from the suppliers. I have shown 1 3/8” on my sketch, which is MORE than 1 1/4” (5/4”). But I think we could live with the 5/4” width, particularly if #12 screws are adequate given the nature of the fibreglass.


Now we have to consider the “cut” of the plank. It could come either “plain-cut” or “rift-cut”. Plain-cut is the standard with the growth rings running from edge to edge of the plank. Rift-cut means that the growth rings run from side to side of the plank. Because the rails are higher than they are wide it would be natural to cut them from a plain cut plank in such a way that the growth rings run from top to bottom of the rail. This may APPEAR to be what we want, since the easiest bend is when the bend is at right angles to the growth rings. However, the LEAST adhesion between one year's growth and the next occurs where the growth ring is (the boundary twixt each year's growth). That has the result that if you stress the wood sufficiently in a direction normal to the growth ring, one layer will let go from the next. That is why the wood breaks when you are bending it.


So it would be hetter to have the rings in the rail run horizontally. Maybe that seems counterintuitive, but that is what would confer the greatest “break resistance”, because the stresses of the bend would then be taken internally by each of the many layers between growth rings.


A little late for that now I suppose. Depending on how much money you are willing to sped, you could have new rails milled from a 3” plain-cut plank or from a 2” rift-cut plank. Price of T.grandis being what it is, I don't really think that I would go that route myself :-)!


A whole different approach to a sweet little traditional looking boat like a Skimmer is to use “plain commercial finish”, i.e. paint. We used to make fun of the yotties with comments like :Sure I'm gonna use varnish – white lead varnish”. “White lead varnish” is, of course, ordinary white paint which in those days before the coming of the EPA was lead-based. Rubbing strakes might be painted black and toerails green. But brightwork? Leave that to the Sunday sailors :-)


TP

[NevisDog]

Originally Posted by TrentePieds

lessee if this did it then...

Beautiful sketch, TP ... but it clearly shows room for a nut/washer to be slid in under the deck liner for through-bolting. That would be the perfect solution but somehow I doubt it's that simple.

I also think less height in the toerail may reduce through-life loads on those fasteners and glue - from bumping alongside, pressure from fenders, crew bracing feet against it, etc, etc. No problem bending/clamping a steamed square section into shape, for example.

[Cadence]

You might consider a steam box. How it works with oily teak? What about cutting the teak for the hull curvature and laminating it and screwing it down a beveled plank at a time?

[TrentePieds]

Nevis and Cadence - and Tatheel, of course:

Thanx for the compliment :-) I left the deck to hull joint vague because we have NO way of knowing what the builder/factory did in this area. The moulding/assembly sequence has to be such that this area is the 'weakest link" in the construction of the boat. I doubt very much that you can get in there without doing invasive surgery. So screws will have to do.

Now, if the boat were mine, I might get agitated enuff to do the exploratory surgery in a place where evidence of its having been done can be obliterated.

The height of the rail is not enuff at 2 1/2" to capsize it, since the base width is 1 3/8". Stanchions don't come into it because, even if the boat had them, they would not, or at least they should not, be connected to the rail in any way.

Steam bending works only on a few species of wood. Teak ain't one of them. I'm really not much of a teak fan, since IMO the only clear advantage teak has over many other species is that it requires no finishing. If fact it doesn't take conventional finishes well at all, because it is so oily. "Modern Danish" furniture was made from teak, back when it was in vogue, precisely because the factory saved on labour. All you have to do with teak is rub more oil into it - Watkin's "Danish Teak Oil" - which is no more than boiled linseed oil with some tung-oil thrown in as a hardener. You simply COULDN'T french-polish teak if you tried!

Varnishing exterior teak exposed to weather is simply an invitation to hard labour. Rub down and varnish three times a season. Who needs it? If you are going to use teak then let it weather in its natural way to that dull grey appearance it gets. Because it is a wood with little abrasion resistance you can "holy stone" your decks to keep them clean if you have laid teak decks - which God forbid :-)! Rails and such just need an occasional rub with garnet paper.

Below decks where liquid water is a rarity there are many other species I prefer, and these days when so much of the furniture is made from plywood, I really like the light finish of birch-veneered ply. If you like "accents", then use a bit of Honduras mahogany (Swietiana macrophylla) or, if you've got money burning a hole in your pocket, "rosewood" (Dalbergia latifolia)

TP

[sailingharry]

Originally Posted by jhulmer

If the Teak toe rail is not clear drilled for the screw all the way through then the screw will bite into the teak and tighten before it bottoms out in the fiberglass.

This is your issue. The holes in the rail must let the screws pass freely.