Genuine Post About Real Boaty Things

[Lakesailor]

Just in case you thought I was trying to sell some tat.

I'm about to steam a new gunwhale strip for the Mirror clone (West 11) I bought the other day. Well, half of it to be correct.

That's the old split one and the new bit of Iroko. I had a groove and profile cut in it by the supplier.
It fits on the top of the mouldings.

So I need to steam it to take on the bend. I've made a steamer.

and got my source of steam

The question for the panel is. How long will it need steaming and should I try to bend it onto the gunwhale, or should I make a former from a plank with blocks nailed on, to make it easier to clamp in position? Hoping it will transfer easily to the boat once cooled and dried.

 

[AIDY]

sorry no help here. but it looks an interesting project. i will watch and learn.

by the way mine's a tea, white no sugar /forums/images/graemlins/grin.gif

 

[mikemonty]

I watched someone on a Discovery Channel programme steam a length of hickory about that thickness and bend it through more than 180 degrees after 45 minutes steaming.
It may be different for a hardwood - but my understanding is that its actually the heat that makes the wood pliable - the steam is really only a "non scorching heat delivery system".
Being a coward though I'll add "don't blame me if..."
I'd suggest a test piece.

I will add that the lacrosse sticks he was making then went for seasoning for (I think) several months - probably not critical where you have both a gentle bend and the boat holding it in shape.

 

[Sans Bateau]

No one can say Lakey is a victim of high tech solutions /forums/images/graemlins/grin.gif

 

[Lakesailor]

Only the one bit and I have to get it right in one attempt as it won't go back in the steamer once it's bent a bit.

 

[john_morris_uk]

1. You might have to insulate the pipe a bit. (You will steam at one end and just get condensate at the other if you are not careful)

2. Try an hour and then give it a go. I can't tell the thickness from your picture, but if its as thin as I'm guessing half an hour might be enough.

3. I'd put it straight on the gunwale, but you might need some help.

4. Get some gardening or welding gloves to hold it with once its out of your steamer.

 

[MoodySabre]

I've never done it but wouldn't have thought that bending on the moulding won't be quick enough (or the moulding strong enough). A jig would seem the way to go
http://www.allwoodwork.com/article/woodwork/methods_of_bending_wood.htm

 

[Lakesailor]

Good points.
I have some 4" plastic pipe which may allow more even distribution and I could cover it with an old duvet or something.

Second pair of hands a bit tricky. I may make a former anyway and if things aren't going well on the boat transfer to that.

Gardening gloves on standby.

 

[Tranona]

The rule of thumb is 30 minutes per sq inch of section. Iroko is not the best timber for this application as it can have very wiggly (?) grain. Would not try and get it to go over the gunwhale in one go. Probably better to bend it round a former such as the other side of the boat upside down of course to get the set the right way. Clamp it aft first and gradually pull it in toward the bow, clamping as you go. Let it cool to get some idea of how much springback you get. You will also then have a better idea of how to cut the mating surfaces to fit.

Good luck.

 

[mikemonty]

I suspect that once you have steam giong through your poly pipe it will be at least as pliable as the wood!
You could probably easily force the half-bent bit back into the tube (all assuming the tube was, as previously suggested, insulated, which would keep it hot too)

 

[catmandoo]

Three comments

1 Put a slope on your pipe to remove condensate
2 your kettle may run dry too soon . Try a wall paper steamer it holds a lot more . you could also get a better connection with the steam pipe and the stripper pipe by fitting a plastic tee at the hot end capped and at the tee end a reducer to connect the steam pipe to . Then leave a bit sticking out so you can get a good grip without scalding your hand
3 As with most hole situations your withdrawal technique must be quite sllck so you can pull it out and get it into the Jig which I presume you have previously made ( If not would suggest a flat board with holes drilled for pegs to get the shape you want ) And as the actress said to the bishop -" pull it out quickly and dispose of it without any fumbling or mess and let it cool off ready for next time "

 

[Lakesailor]

Slope : Good point.

No wallpaper stripper. But I can top-up kettle with boiling water from electric kettle (gardening gloves again)

I've made a former using the old capping piece to get both curvatures.

I can whip it out easily. I have some 6" land drain plastic pipe in case this doesn't do the trick.


Stand back. I'm going in..........

 

[Norman_E]

Iroko is not the easiest wood to bend, but you can improve your chances of a good result by making a substantial jig.

I suggest a scrap piece of kitchen worktop for the base (as a plank may not be wide enough), with the boat shape drawn onto it, by laying the hull upside down on it and drawing round. Then draw another line to get an accurate representation of the inside of the bend. Screw on wood blocks at close intervals on the inside of the curve so that you can bend the wood before it cools, and clamp it to the blocks to set, using as many clamps as you can beg borrow or steal. One very good tip is to fit the jig with a fixed block on the outside of the curve at the end with the greatest curvature, so that you put that end of the wood between two blocks and bend it by pulling the other end towards the row of "inside blocks".

As to time steaming, as others have said it is heat, not moisture, that makes wood pliable. I think you need a larger diameter tube, with some lagging wrapped round it, and a big supply of steam. Two electric kettles, used alternately for an hour, should do the trick. Just make sure that the second kettle is at the boil before the first runs too low and needs replacing.

Two pairs of hands are very useful when it is ready to bend, one to get the wood into position and bend it, and the other to get the clamps on as quickly as possible.

 

[floatything]

I'd be tempted to do a scarf joint where the new joins the old - to avoid a weak point.

 

[srp]

You'll need more blocks on that jig to get a fair curve, especially with iroko. This is for laminating, but I would make the same sort of thing for steaming (in fact I have a scaffold plank which I set up for steaming rubbing strakes):

Don't forget the heavy gardening gloves to get it out of the steamer with. And a shedload of g-cramps as well. It'll stay pliable for about a minute at the most.
Because of the shape of the moulding, it would be worth putting some strategically placed softwood blocks in the groove (wedged in is fine) so that when you clamp it up you don't distort or split the section. Steam it for about an hour, but I would pre-soak it if it was me - overnight wrapped in wet cloth would be fine. The wetness factor is purely because water is good at transferring heat into the wood. It's the heat that makes it pliable. After steaming leave it for at least 24 hrs in the jig. It will spring back quite a bit, so bear that in mind when you set up the jig ie overbend it. I use a 4" plastic soil pipe (which goes very soft after an hour) and a Wickes wallpaper stripper. Folded rags to bung up the holes at each end, and a fall to drain out the condensate.

 

[pampas]

Have done a bit and found that the radi needs to be a couple of inches tighter than what is required,as the lovely steamed section cools quickly and settles to its own shape. Would suggest (As mentioned before) 4 hands plenty of clamps, take out of steamer and place in jig asap. A good 45 minutes should do the trick, and dont forget to stop up the kettle steam vent, have enough global warming as it is. Not an expert by any means. Best of luck and good steaming.

ps. partially close the end of the tude when fired up with a loose rag,helps keep the steam flow more even during transition up the tube.

 

[Lakesailor]

Already done a scarf joint at one end

We're off. I have blocked the vent

Steamer's droop

Now insulated with some old dralon curtains

More soon, been going 40 minutes now.

 

[Bilgediver]

One of those wallpaper steamers are much more efficient and come with a hose....just remove the attachment at the end.

 

[Lakesailor]

Erm.......job's done. Didn't have to hire anything. Although the kettle was at the end of it's capabilities, a longer steamer would have been more than it could manage.

The old split capping piece is on the right. I've introduced more bend in the new one to allow for some springing.

The bend in mainly in the middle so I don't think I needed too many chocks.I replaced the end chock with a removeable pin as I couldn't get the wood bent enough and also over the chock. with the pin out I just slid the wood across and dropped the pin in.

You can see the bend on the boat is mainly where the arrow is.

Thanks for all your suggestions, particularly angling the steamer and insulation.

 

[Ruffles]

I replaced the cap rails on our old dinghy with two pieces. Partly because that's how it was originally but also I thought it might twist as I bent a shaped section. Mind you I think each piece was 3/4" thick so thicker than yours? I then planed a rebate in the outer curve of the inner piece after I'd steamed it. You can just see the first bit on the dinghy in the piccy.

I found it was hard to get a curve at the bow end so I left the timber a foot too long and trimmed after steaming.

I steamed a 6" section at a time using an indian take-away box. Just cut slots at the end to take the timber and a hole to take the pipe from a steamer. Clamp to end of workmate. Steam for 10 minutes and apply pressure. Boring job - best done while listening to cricket.

The original timber had been varnished and the dinghy had been left upside down. This is a bit of a problem with a wood rail on a GF dinghy since water gets in to the gap and can't get out. I bedded mine on with cheap Sika polyurethane glue from Travis Perkins. They are also screwed together. I then poured copious quantities of Rustins teak oil down any gaps that were left. That was 3 years ago. I sanded it down and re-oiled it last w/e 'cos it was starting to look a bit rough. In half an hour it was good as new.

I made one major error. The thing is kept in a rack on its transom. I should have left limber holes in the rail at the back 'cos water accumulates inside.