How do you straighten a short wood mast?

Zagato

Zagato

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The mast is 16' long and solid not hollow. It has been used to hold the boat cover up and now dips in the middle.

I am thinking stands at either end with a weight in the middle and maybe towels with hot water poured on them or is that ridiculous.
 
No, not ridiculous.
That's an approximation to 'steam bending', which is a well-known traditional boatbuilding technique. You'll be aware that wood contains a percentage of water in its cells and asymmetric bending-loading over time 'squishes' some cells, 'stretches' those opposite, to give you the dip you've experienced.
It'll take time to change. Be aware that you may need a system of restraints to prevent it bending at other than the wanted 180degrees back to straight.

Do you have a wooden boom? I do, spare, and if you're interested send me a PM/DM and I'll go measure it up.
 
If you have lots of time - then 'cold bending' as you ask is possible..... care needs to be taken that you do not create opposite bend.

The quickest and best way - is the steam box ..... basically a tube large enough for you to slide the mast into and has a steam generator at one end and limited exit at other .... the tube inclined with lower end where steam enters ...

The steam needs to be a continuous supply ... doesn't actually need to be large volume .. but steady so it fills and passes through the tube or box.

The Steam causes the fibres to soften and allows you to then bend the wood as desired. For your mast .. I would suggest constructing a box with a removeable top and wedges - so mast is placed in .... top put on ... steam introduced .... leave it steaming .... then carefully remove top and using the wedges - straighten the mast in the box. Put top back on .. steam again ... then remove top - check mast is straight with wedges still in place ... let it cool.

Once cold - remove wedges and mast should be OK.

Steam generator ? Small DIY Steam Cleaner will do it .... or a fire and drum of water - with spout into the tube / box ...

 
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I have had some success with a heat gun on smaller pieces of wood. Apply the heat to the inside of the bend and slowly bend it in the required direction. I don't know how well it would work on a mast but it is easy to try.
wood bending
 
Softly, softly, catchee monkey!

Keep in under your boat cover, wedged with the bend upwards. Over time (and especially in damp weather) it will gradually reduce and then eliminate the bend.

Once it is straight, arrange support along the central part of the length (or an alternative support for the cover) so that it does not take up a reverse bend.
 
Thanks for the replies. At the moment I have it resting at either end on two patio chairs with weight on the middle. This crazy heat does seem to be straightening it out slowly. The jury is out, it needs a few more days I am hoping.
 
As others have stated, it'd be easy to 'over correct' the bend, so it could be worthwhile fitting a stick of wood between the mast and the ground to take the weight once the bend is removed.
I hate to say it as well, but I was under the impression that wet heat was far more effective than dry heat for this, which might work for you, if you were to wrap it in black cloth, soaked in water outside in the sun, perhaps?
I speak as a non expert.
 
I agree that it's moisture you need, I think, to allow the mast's cellular structure to be reconfigured. The low humidity in current weather won't achieve that as well as the traditional damp British autumn and winter.

I'd be wary, too, of attaching a single weight in the middle. I imagine that the weight of the canopy that first caused the bend you have would have been spread more evenly along the unsupported length of the mast, and you may perhaps find you end up with a shorter, sharper corner -like bend in the middle of the mast in one direction without fully correcting the longer, gentler bend you currently have in the other direction.

Good luck whatever you do. Do let us know how you get on.
 
Refueler said:
If you have lots of time - then 'cold bending' as you ask is possible..... care needs to be taken that you do not create opposite bend.

The quickest and best way - is the steam box ..... basically a tube large enough for you to slide the mast into and has a steam generator at one end and limited exit at other .... the tube inclined with lower end where steam enters ...

The steam needs to be a continuous supply ... doesn't actually need to be large volume .. but steady so it fills and passes through the tube or box.

The Steam causes the fibres to soften and allows you to then bend the wood as desired. For your mast .. I would suggest constructing a box with a removeable top and wedges - so mast is placed in .... top put on ... steam introduced .... leave it steaming .... then carefully remove top and using the wedges - straighten the mast in the box. Put top back on .. steam again ... then remove top - check mast is straight with wedges still in place ... let it cool.

Once cold - remove wedges and mast should be OK.

Steam generator ? Small DIY Steam Cleaner will do it .... or a fire and drum of water - with spout into the tube / box ...

Click to expand...

I would echo what Refueler has said. A domestic steamer (or two) into a length of drainpipe would work for this purpose. The hardest task is going to be making a jig to straighten the stock it as it needs to dry out in the straightened position. No mean feat. Personally, for your purposes, I think I'd be looking at a length of steel I-beam and a lot of strong straps or clamps, with additional people to help apply them, as its a time critical task.

Plenty of video's on steam bending available on youtube and the amount of clamps used may surprise you. Wood is so strong, it always wants to do it's own thing and isn't easily persuaded otherwise!
 
If you want to clamp it to a long straight edge then use clear polythene tubing (we buy from a catering supplier). Put mast and one or more steam tubes into the bag (domestic wall pare strippers are ideal). Once upto to temp and pressure leave it for an hour per inch of width. You can then strap the whole mast/bag to the straight edge. Leave to cool and it should be fine.
 
Well weighting it down in the middle made no difference whatsoever but with quite a bend attaching the forestry pulled her straight. I was lucky they rested the mast on the front due to the fittings and not on its side. Another problem I didn,t need to worry about. Thanks for your replies.
 
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