Clamping Challenges

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Cyclone
Posts: 60
Joined: Sun Jan 08, 2012 7:26 pm
Location: Barrie, Ontario

Clamping Challenges

Postby Cyclone » Thu Sep 18, 2014 4:45 pm

I am building the Glen L, Blue Fin. I found it challenging to apply the side planking to the hull, especially at the bow where the side planning meets the stem. This this design has a reverse cure near the tip of the stem. The design of the bow also has a considerable amount of flare and uses harpins to make the curve from the shear clamps to the stem. Each of the side planking panels were made in one piece by using scarf joints to connect three 4’ x 8’ sheets of plywood end to end and then cutting out the side panel shape. The finished side panels are just over 22 feet long to allow for the curve at the bow. The hull is 19-1/2 feet long. I thought I would share my experience with others in case it might of help. I got lots of good helpful information of this site and hopefully this might help somebody else.

I was able to install the first side planking panel using a clamping arrangement against the back of the stem to force the plywood into the reverse curve of the stem. When applying the first panel it was easier to clamp because you have access to the back side of the stem on the opposite side of the hull from where the panel is being applied. After the first panel was installed the clamping became a challenge as there is really nothing to clamp to due to not having access to the back of the stem. I was not using any steam or water to make the panel more flexible. I did not want to use water or steam unless absolutely necessary. I would estimate that it was taking 300 pounds of force to get the plywood to conform to the reverse curve. I was using only 1 clamp at the lowest point on the midpoint of the radius (center of the reverse curve). I found that once the material was clamped here, the panel was making contact along the full length of the stem and there was no need to add any more clamps.

Before tackling the application of the second side planking panel, I needed to find a suitable method and test it thoroughly. Once you have applied the epoxy to all the contact surfaces of the 22 foot long panels and to the hull framing the clock is running. You do not have time to deal with clamping issues. I tried using heavy ratcheting cargo straps, but I found it difficult to get them to remain in the correct position during loading. Also it seemed to me that the ratchet mechanism was being pushed to the breaking point. I also tried using some 3ft long heavy bar clamps along with heavy blocking applied to the building form to clamp against, but in testing this proved troublesome. Sometimes it worked in testing and other times it was too much of a fight to get the clamp and panel into the correct positon. I did plan to use slow cure hardener with the epoxy when I applied the panel permanently as to give myself more time to complete the job.

I will attach some pictures of what I came up with and successfully used in the end. The first picture shows a 6” C-Clamp where I cut off one end with a hack saw and installed the threaded rod in the opposite direction. This allows the clamp to be positioned on a 2” x 4” with another piece of wood as a spacer. Next I build a frame out of 2” x 4” that positioned this clamp at exact point where the pressure was needed. Additional blocking was added around the clamp to support it so that it could not move under load. I connected the clamp support framing to the building form with 2 heavy screws in such a way that it could be swung in and out of position. This allowed the side panel to be positioned on the side of the boat while the fasteners and clamps were applied starting a amidships and working toward the bow and stern. Once the panel was partly installed and in position near the bow, the clamping frame was swung into final position. Next additional screws were added to the other supporting members of the clamp framing to ensure nothing moved or broke under loading. At this point the threaded rod on the clamp could be turned to draw the panel into the radius of the reverse curve. A piece of wood was used between the plywood and the end of the clamp to spread the force over a greater area of the panel and to prevent it from being damaged.

Sorry for the pictures not showing more details. I am having trouble getting pictures of my build as the garage is 12’ x 20’. With the hull being 19-1/2 feet long with a maximum beam of 7’-10”, there is no room left in there to stand back and get more detail in the picture. The building form is on wheels and I often open the door and move things a few feet outside. I work on one side of the boat at a time and then wheel is out into the drive way for a “U” turn before going back in to work on the other side.
Perhaps some may think that this seems like too much work on devising a method for clamping, but for me it was worth it considering what I already have invested at this point. You only get one first shot at applying those big panels successfully at the first attempt.
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DanielKa
Posts: 1
Joined: Wed Feb 17, 2016 10:52 pm

Clamping Challenges

Postby DanielKa » Thu Mar 10, 2016 3:27 pm

Ive just been offered one of these. Its a new one to me and Id be interested to know a bit about it. I dont especially want it myself but if anyone else does, Ill grab it and hold it for you. I doubt it will be expensive.

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psychobilly
Posts: 994
Joined: Wed May 12, 2010 3:07 am
Location: Tomball, TX

Re: Clamping Challenges

Postby psychobilly » Sat Mar 19, 2016 8:17 am

Pretty kewl idear!

FYI in Australia they are not called "C" clamps, they're called "G" clamps. Lol you say potato and I say tater. :lol:

Thanks fer share'n

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gap998
Posts: 378
Joined: Wed May 20, 2015 5:40 pm
Location: Wales, UK

Re: Clamping Challenges

Postby gap998 » Sun Mar 20, 2016 4:36 pm

G-Clamps in the UK too. :)
Gary

Planning a whole fleet, but starting with a Zip...I think.

"Just when you think you've made something idiot-proof, someone builds a better idiot!"

User avatar
psychobilly
Posts: 994
Joined: Wed May 12, 2010 3:07 am
Location: Tomball, TX

Re: Clamping Challenges

Postby psychobilly » Mon Mar 21, 2016 8:41 pm

Lol, I think when our ancestors came across the big pond, they must have really wanted a new change in every part of their every day life. Lol So many everyday things changed, even simple little things like G Clamps to C Clamps. Lol


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