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Fairing the sides on the malahini transom

Posted: Fri Sep 29, 2017 7:45 am
by nate_db
Hey guys,

A little over a year ago i posted on the forum after ordering my malahini plans. I worked a lot on it during the summer and i'm now about 80% finished fairing the hull. For a while now i've been stuck on the back end of the boat. Is there an easy way to fair the sides of the transom to make a nice curve in the side planking from the first frame to the transom? When i cut out the transom shape i did the sides with a 90° angle. Suggestions?

Kind regards,

Nathan

Re: Fairing the sides on the malahini transom

Posted: Fri Sep 29, 2017 8:44 am
by PeterG
Hi Nate! Sounds like you have been busy!
Some people here use a power planer or belt sander for removing most of the material and finish the shaping and beveling by hand. You can use a small low-angle hand plane to bevel the edges of the transom to the proper angle, and finish the edges with a sanding board. The bottom edge is beveled to 13 degrees but the sides are more complicated. That angle varies from the top corner at the sheer clamp to the bottom corner at the chine. To get the proper angle along the curve, you can use a batten applied at intervals down the edge of the transom and the frames. You remove enough material so the batten makes full contact along the edge of the transom.
When you made your transom, you left extra material on the bottom and side edges like the instructions said? The pattern for the transom is applied to the aft face of the transom plywood. That pattern could be used to lay out the edges of the transom and you can bevel the edges close to that line and then finish the bevel for best fit using the batten method. Think of that line on the aft face of the transom as a control, it has the shape you want, it dictates where the corner is between the transom and the sides of the boat, therefore the bevel on the edge meets that line and angles outward.
I hope this helps, always feel free to ask questions. Have fun and post pictures of your project!

Re: Fairing the sides on the malahini transom

Posted: Fri Sep 29, 2017 9:41 am
by Jimbob
Hi Nate,
What I did on my boat was to follow the natural curve of the battens to get final shape my transom. My boat is different, but the concept might work for you. I don't think you have battens on the sides on your boat, but you could clamp one on just to get the natural curve. Like Peter G. suggested, I would use a batten to mark on the transom where that curve would end up. Move the batten and keep marking on the transom where the curve ends up. Connect the lines and you have a cut line on the transom. Cut the transom with a jig saw leaving room for final shaping shaping with a belt sander, following the natural curve of the bottom and sides. I am assuming that the transom is attached. If not, I would temporally attach it just to get the cut line. Hope I understood your question, an that this might help. See pic of what I did.
Jim

Re: Fairing the sides on the malahini transom

Posted: Mon Oct 02, 2017 2:27 am
by nate_db
Thanks for the replies Peter and Jim. I think i skipped the "leaving a a little extra on the sides" memo. I will try and fix this by using the pattern on the transom, draw the sides just a little more inwards so i can continue the curve for the side planking. As you said peter, the line on the patters have the shape you want to get. Hope the fairing part is over soon enough! As for now, here's a picture after i attached my sheers!

Re: Fairing the sides on the malahini transom

Posted: Mon Oct 02, 2017 4:26 am
by PeterG
That looks great!
You can fair to the transom as it is, it will change the shape of your hull slightly. Although changes in that area will not have much effect. But you should be able to fix the transom by adding some extra wood to make it fair in properly. You can laminate thin strips in a couple of layers to the edges of your transom and gain enough material to make your bevel. Thin layers will bend easier to the shape of the transom. When you install the plywood sides the extra material would not be visible.

Edited: Actually I studied your photo and see your chines and sheers are installed to your transom. Your method of fairing will be best. You can check your fairing progress with a strip of plywood laid against the sheer, chine and edge of the transom, maybe 4-6 inches or 100-150mm wide. You can see where you need to work the transom for good contact. Great looking work so far. Love the lines of the chines and sheers, you have a great start.

Re: Fairing the sides on the malahini transom

Posted: Sat Oct 07, 2017 1:43 am
by nate_db
Thanks for the help peter! One side is now ready for the planking, the other side had to be built out a little. As for the side planking. Is it possible to attach and glue the planking to the chines first and after this has set, fix the planking to the sheers? Or do you have to attach the whole side planking in one go? And another thing. Are there any plans or dimensions given for the skeg and spray rails on the sides? Oh and when you butt joint plywood panels, how do you conceal the joint on the outside? Woodfiller?
Sorry for the load of questions!

Re: Fairing the sides on the malahini transom

Posted: Sat Oct 07, 2017 4:28 am
by DrBryanJ
Nate:

I think everyone applies the planking in "one go". I did butt joints and they came out pretty tight. A little thickened epoxy filled any gaps. I don't remember if there are plans for the skeg (haven't gotten to that yet on my build.) I know there are no plans for the spray rails, just suggested profile, which i can't look-up right now because I'm at work.

Re: Fairing the sides on the malahini transom

Posted: Sat Oct 07, 2017 10:30 am
by hoodman
I think you could run into a good bit of trouble gluing to the chine first and letting that cure. Are you trying to finish the plywood bright (natural)? If so you need to be really careful about getting the butt joints as tight as possible and maybe attempt to match the grain up if you can. I have seen several pictures on the Glen-l site with bright finished hulls with butt jointed ply. They don't look bad in my opinion but I was not able to get tight enough fitting joints myself so I am going with painted sides.

Re: Fairing the sides on the malahini transom

Posted: Sat Oct 07, 2017 10:18 pm
by PeterG
You are making great progress!
It is best to install the planking in one step, The plywood will flex into place with the proper curvature and will be less risk of trouble than doing it one edge at a time.
The skeg dimensions are found at the bottom of sheet 2 in the profile view. The spray rail dimensions are found just left of center on sheet 4. The spray rails are installed on the lower edge of the sides from stem to transom according to the drawing. Now, there are also bumper rails on the side, shown in the sheet 2 profile. Sometimes folks call those spray rails too, but really they only serve to protect the side planking.
As far as the side butt joints, if your plywood is finished with stain and varnish, the joint will show as a line. It can be filled as needed with a wood putty called famowood to smooth it out. But most people here apply fiberglass on the outside of the hull and the butt joints can be faired with epoxy. Many have painted their hulls and then did a stain and varnish finish for the deck (referred to as a bright finish). I intend to paint my hull and install a traditional deck just like Chris Craft and Hacker Craft did using planks of mahogany.