The Black Art of Steamed Ribs

Three new oak ribs in the BB.

Steam bending ribs is one of those skills that you might use once in a lifetime unless you are working fulltime in wooden boat restoration. This part of the work on the BB11 has taken more research than any other, the time spent has been worth it. The first rib was steamed and screwed in last Saturday and is perfect!

Raw timber, unseasoned oak lengths and some offcuts.

First find your ribs.
Unseasoned timber is hard to come across, not impossible, just difficult to find. The best source of timber to emerge from all our searching was John Hall Saw Mills, Bleasby near Nottingham. Established in 1856 the company has progressed from wheelrights through coffin making to specialising in quality english timbers for boat builders. After a couple of telephone calls to John it was decided that an Oak log of suitable age was available. The log was only a few months old and very 'green'.
This is new territory for me, I am used to buying timber from specialists but this was something else. Also the fact that the wood was going to be steam bent added another dimension. I found lots of people who knew about steam bending but hardly anyone who had done any. There are quite a few web pages about steam bending and they have all been helpful, I hope my experience of the process helps someone in the future. Follow the rules and there are no problems!

Having selected the right timber, in our case English Oak, cut enough spares to discard the pieces with knots and other obvious faults. Then be prepared to break some as they are bent into your boat. About 20% spares should be right. Please bear in mind that we only have 23 ribs to replace, if you are doing a hull with more you should look at a better 'production line', and recruit more hands to help.

A domestic wallpaper stripper is excellent for low volume steaming.

Next, steaming your ribs
Steaming is steaming regardless of the equipment you use. I did not want a 50 gallon drum of water boiling over an open fire so I decided to opt for a smaller system. The Earlex steam unit is designed for domestic uses such as carpet cleaning and wallpaper stripping but it does the main job of making steam. On one filling it will run for 90 minutes which gives us enough steam to do two ribs before refilling. It is also safe to use.
Our steam box is a 6' length of industrial plastic drainpipe, the feeder tube from the steamer is pushed in one end and stuffed with rags. The unit is switched on and after about 10 minutes steam begins to flow, this is important, steam must flow through to work its magic. Our rib is pushed in and the other end is loosely stuffed with rags, steam is allowed to escape.

The shortest and deepest curve to need a new rib - if we can do this the rest is easy.

Out of the frying pan...
Using the universal rule of one hour steaming to one inch of timber the rib is taken out after 60 minutes and rushed to the boat which is only about five feet away. With myself in the boat and Liz on the outside with electric drill, screws and screwdriver a five minute wrestling session ensues. The steamed rib starts to lose its ability to bend the moment it is taken from the steam box. The first 20 seconds are critical and you should aim to have the rib in place very quickly. you then have time to hammer the rib around until it is lined up, some pressure will be needed to get the rib to follow the boat's curve as well.

I used one quick-clamp to help keep the rib in place while I put my weight onto the rib as Liz drilled a pilot hole and put the first 4 or 5 screws in. I then climbed out of the hull and completed putting the screws into the new rib. It worked, I don't know why I was so surprised, we followed the rules, selected the right timber and worked quickly. Just like baking a cake.
Once the rib has cooled it sets like stone, it will unbend a little but if you try and bend it into a deeper curve it will break. Steaming also helps to solve the problem of rot that occurs with unseasoned timber, a further treatment with Intertox will help as well.

After our first success the following three ribs looked better than the first, we relaxed a little, more haste -
less speed. After doing four ribs we are now confident that the rest will be ok and we can move on to the next stage of our BB's restoration.

The state of play so far - 4 new ribs and an almost complete strip down to bare wood.

Steaming Tips
1 - Get good timber for your ribs, unseasoned, straight grained oak is what we chose.
2 - Use a reliable source of constant steam, interruptions in the flow of steam creates firewood.
3 - Work quickly and have all the tools you need to hand.
4 - If in doubt experiment until you get a system that works.