Mahogany bending toe rail

[PAUL BARRETT]

I have read various threads on bending mahogany, and it seems to be problematic.
Here is what I'm doing what do you think.
I am replacing the toe rail cap with a piece of 1/2" x 2.0" mahogany, bending across the 2.0" dimension.The tightest bend is about 4"/ft. Can't I steam this without presoaking.If I do need to presoak, does this mean I have to put each 12ft section on at a time and let dry. (I HAD SEEN THAT QUESTION ASKED BEFORE BUT DIDN'T FIND A REPLY)

[Art Read]

Four inches in a foot seems pretty tight... But then I've never tried to bend 2" Mahogany stock before. I think my cockpit coamings probably pushed the limits of Mahogony's bending "forgiveness" and I'd guess they had to take a curve similar to what you describe up towards the forward end there. Perhaps a sacrifical "test" piece of the wood you intend to use, steamed for an hour or two and clamped home at the worst of the bend would be "instructive"?

http://www.imagestation.com/picture/sraid60/p03c6461c0fb7705a8ed07a26b9002940/fc463c47.jpg

[ishmael]

Why not soak it Paul?

I've bent similar coamings to Art's. Broke one piece of stock because of grain run out. The last two went fine.

I dunno, but soaking it wouldn't hurt.

[Carlsboats]

Mahogany can be tricky to steam bend. I just finished making coamings much like the ones pictures in the post here, 7" high by about 12' long. The fwd. end bends about 16 inches in the five feet. I had to laminate it in two pieces, each 7/16" thick -- could not see any way to take a 3/4 to 7/8 mahogany plank around that tight a curve otherwise. Did the bending on a jig, made to a tighter radius than needed to allow for spring-back. The front six feet of the coaming stock was put in the steam box for 35 minutes, then immediately clamped to the bending jig. Left for two days to dry, then glued the two laminates together on the boat, using the carlins and some temporary angle blocks on deck to establish the shape.
There was a lot of spring-back after steaming -- much more than you would get with oak. Mahogany is like that. But was able to pull the two laminates to the final curve with clamps, and once the glue dried, the coamings are holding their final shape okay.
Hope this experience os of sume use to you.

[Paul Scheuer]

Paul: If I understand it right, you're talking about bending in the plane of the 2 inch dimension (a 1/2 inch wide board). I'll predict that you're in for some tough sledding. At 4 to 1 it's going to want to pop out of whatever you use to clamp it.

I'd suggest bending at least a square board clamped to a bench fixture and cutting it after it has cooled/dried/aclimated to its new shape. That would give you a chance to see which way the piece prefers to bend.

[willmarsh3]

This weekend I decided to work on the toerails for my Elver. I built a steambox that takes about as much steam as I can generate using a turkey fryer. Yesterday I put 3/4x1" stock in, steamed it for an hour and clamped it on the boat. It worked ok. Today I tried to steam more pieces to complete the toerail and ran into difficulties. I modified the steambox to make the pipe carrying the steam from the turkey fryer to the box so it would carry more steam but still had problems bending the wood on the jig after steaming. My questions are as follows:
If I put a piece of mahogany in and not steam it long enough, then take it out, try to bend it on the jig, then put it back in and steam again does that make the wood less amenable to steam bending?

Will.

[ssor]

Why not take that stock to the saw and rip it into 3/8 inch pieces, keep track of the order of the grain and laminate the curve. If you work carfully and keep the grain pattern it will be almost undectable. I have done it successfully with black walnut.

[seayou77]

Since you are bending on a jig; try wraping the stock with plastic and put the steam right to the piece as you bring it in with clamps.
A batten of wood will help contain the outer fibers from splintering tho. most use steel, which will blacken your wood.
Just what kinda turkey fryer you cookin with?

[willmarsh3]

Thanks for the help. I thought about laminating but wanted to get experience with the steambox. I think it will turn out ok but if not, then I will laminate/glue in place using finishing nails driven in the deck as a jig. Later I will patch the holes with epoxy.
The turkey fryer is a large burner I got at Walmart that works with a portable propane cylinder. The vessel is a 10 qt pot. This burner sets this filled pot to a full boil in about 5 min.

Will

[Brian Palmer]

Will Marsh,

I put new toe rails on my Elver with no steaming. They were 3/4 thick by 1 1/4 high yellow poplar (mahogany may be different) and I just bent them into place and put the screws in. I used Boatyard Bedding Compound between the rails and deck.

-- Brian

[ssor]

Brian, planning to replace them on a schedule of three or four years? Yellow poplar is not at all durable. :confused:

[Brian Palmer]

SSOR,

Well, yes, yellow poplar is not the most durable wood, as I have since learned from several other sources. But, it was the best alternative I could find locally. Fortunately, they are just a "screw on" piece and not integral to the structure of the boat. I've since located a better lumber source close to home.

FWIW, the white oak rails that I replaced were rotten, too. They weren't bedded properly and started to rot from the deck up. They were also installed green and shrank so much in length that they snapped about amidships. So, even with the best materials, you can still make mistakes that make the material irrelevant.

-- Brian