Clipper's Vera Cruise Build

Clipper's Vera Cruise Build

Wednesday, April 16, 2014

Bending The Chine

Bending the chine to curve around the bow of the boat is one of those tasks that I've been looking forward to and dreading at the same time. The thickness of the chine alone is cause for concern because wood that thick generally won't bend enough to get the degree of curvature I needed.

Additionally, I had to cut the notches for the chine in frames 5 and 6, which are the two frames I spent quite a bit of time dressing up last summer. These notches are also more difficult than the straight notches cut at the back of the boat,

These concerns have made me worry about this process for some time. Granted it's only wood and if worse came to worse, I could fix most any problem that arose, but I really don't want to have to do that for two reasons. The expense of replacing the wood and the very real hassle factor of fixing parts that have already been completed. And of course, there is the damage to my pride that would occur.

Nevertheless, this is a necessary task and I now have all the tools and equipment needed to make the bends. I have started down this path and will continue for the remainder of the week. This article will cover the first part of this process.

In order to accomplish the bend, I could have attempted two different techniques.The first technique is to wrap the area to be bent with towels and pour boiling water over them and gradually bend the wood into position. This approach has a few drawbacks. First, it is messy. Secondly the wood is not heated very thoroughly so the amount of bend that can be accomplished is smaller, meaning that more water will have to be used.

The second technique is to use steam. This requires a source of steam and something to contain the steam while it heats the wood. The traditional approach is to build a steambox and heat soak the wood  in the box. When ready to bend, you quickly transfer the wood to the area needed and apply the bend necessary.

One of the challenges I face is the limited space to accomplish this work. A real challenge is how to contain the steam around the bend area and still be able to get that container off of the wood before bending. I had thought of using a large PVC pipe but I have no room to slide the pipe off afterwards.

I recently ran across a different approach to steaming that seemed to offer an improvement on the process of using a steambox and answered the challenges I was facing with lack of space. This technique uses 6 mil plastic sheeting wrapped around the bend area. It has the advantage of allowing the continuous application of steam while performing the bend, thereby eliminating the problem of the wood cooling down too quickly. The plastic sheeting is also flexible and can stay in place while bending. And finally, it can be cut off afterwards.

So the first order of business was to acquire a source of steam. I considered a propane burner and a variety of steel containers, I even looked at a turkey cooker. But most of those were impractical either because of cost or safety (the cooker). Rockler.com sells a steam bending kit manufactured by Earlex that appears to be adapted from a similar product sold by Home Depot for removing wallpaper. It consists of a plastic reservoir with a heating element and a 10 foot length of plastic hose to connect to your steambox


Also in the previous picture, you can see the 6 mil plastic sheeting I bought from Home Depot. I am not sure if a thinner plastic would hold up using this steaming technique, so I bought 6 mil. However, the smallest quantity I could find was a 25 foot by 10 foot roll. Quite a bit more than I need but I figure that I can eventually use the plastic sheeting when I begin sanding and need something to keep sanding dust off of everything in the garage.

I began the process by cutting out a small piece of the plastic that was big enough to wrap around the chine.You need sufficient extra material so you can fold it over and staple the envelope shut. I folded the edges over a couple of times and used ordinary household staples every couple of inches. I didn't want the envelope too tight because I needed to put the steam hose into the end and also have room for the rags to block off the ends.



The rags were folded over a few times and then wrapped around the chine. The bag is slipped over the rags on both ends. This will keep most of the steam inside the envelope. To keep the hose from falling out, I simply tied it in a couple of places to the chine.



Then fill the reservoir with water and hook up the hose and electrical connection. It took about 15 minutes to get the steam going. One other thing I did was to place a bucket under the lower end of the envelope to catch any water that drips out.



The rule of thumb for steaming is one hour for each inch of thickness. I let the chine steam for 2 hours to be sure. The reservoir of the steam generator is not big enough for two hours, so I had some boiling water on the stove and refilled the reservoir when it got low.

A word or two of caution here. Steam is very hot and you need to be very careful when working with it. When I refilled the reservoir, I turned off the steam generator and unplugged it. Then I waited a minute or two to let the pressure subside before opening the cap. I then slowly poured the boiling water into it and wiped it down before reconnecting the electricity. The down time was less than 3 minutes before the steam was going again.




After steaming for a few hours, I used a ratchet strap to pull the chine down to frame 5. It bent quite easily. However, the notch in frame 5 had not been cut yet so I had to let the chine cool over night with the ratchet strap in place before I could continue in the morning. This notch gets cut at an odd angle so I am going slowly with this. Also, the amount of bend needed to get the chine into the notch and down to frame 6 (as well as to the stem) will require a few more steaming sessions. I'll be cutting the notches as I go and bending a bit at a time.

You can see in the last picture that the notch still needs to be cut more, but I have to wait until the chine has dried out before removing the strap. Even with that , there will be some spring back of the wood, but it will be easier to get to that point and move to the next.

So far, the technique has worked as I hoped. I can bend the part while the steam is still being applied and it is quite easy to remove the plastic afterwards to let the parts cool and dry. I will be continuing the process over the next several days with the goal of having the chines ready to install by the weekend.

Until next time, take care.

Update: 9/14/2014

See the update in the next blog entry after this one for more on the results of this steaming of the chine.

Click Here To Comment:

  1. Nice work! Great idea of steaming it in place like that. I'm looking for a steamer to bend some ribs for my boat restoration, thanks for the recommendation. Off to Home Depot I go!

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    1. Thanks Michael,

      I can't take credit for the idea though. I found out about it on the Glen L Builder's forum from a video posted by Jamestown Distributors. The video is Tips From A Shipwright and there are numerous other videos with helpful ideas.

      Good luck with your restoration

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  2. Carl - Glad to see the steam method in action. Here is the original video featuring Louis Sauzedde - http://youtu.be/--iPQIwSEJM Thanks, Tips from a Shipwirght

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    Replies
    1. Yes, the techniques worked quite well. At least one other person has also tried it and he thinks it's super as well. Thanks again.

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