Before I finished installing hull panels, I wanted to get the centerboard uphaul tube installed, while it was still easy to work in that area. This tube lines the hole that the rope runs through to raise the centerboard, and prevents wear to the hole and to the rope.
The uphaul line is 1/4" diameter, so I got a short length of tubing from the hardware store that is 5/16" ID, and 3/8" OD.
First, I drilled the hole. I wanted to ensure that the hole was perpendicular to the bulkhead, and didn't tear out on the far side. So I drilled a hole through a scrap block on the drill press to use a a drill guide, and clamped another block on the inside of the centerboard trunk to prevent tear-out. I drilled a pilot hole and then followed that up with a 7/16" bit.
I cut a short length of tubing, flared the end, and inserted a length of 5/16" dowel and taped it on. This let me manipulate the tubing, rotating it to apply thickend epoxy and pulling it through the hole.
I clamped it in place with a stick until the epoxy cured.
Here's the inside, flared edge.
And this is the other side.
And this shows the 1/4" uphaul line exiting the tube. At this point I considered leaving this as is and calling it done. The rope pulls straight out of the hole and into a turning block, so I think that would work fine. At this point the flaring tool doesn't work, and trying to shape it with a ball pein hammer seemed likely to mess things up.
After some thought, I started rummaging around in my 1/4" bolt bin, and found this flat-head machine screw. My plan was to insert this through the tube with a washer and nut on the inside and flare out the end by tightening the nut in a controlled manner.
Here's the screw Inserted in the tube.
And the resulting flare after tightening up the nut a bit. Worked great.
But it was sticking out a little too far, so I sanded it back using a little disk in a die grinder, and flared again.
And then I did follow up with a little light tapping from the ball pein hammer to fllatten it out just a bit more. Job done!
Dave, Love the photos and detail shots…helping me a lot!! Now a couple questions. First, why does the manual call for 4 CB/Case bushings? I thought it should take 3. 1 for the CB and 2 for the CB case. Am I missing something? Also, I'm considering not building the CB cap. The plans read "Welsford's original drawing did not suggest removable cap". I'm not seeing a great reason to build the cap. What are your thoughts? Brent
ReplyDeleteHi, Brent - you're right that you just need 1 bushing in each side of the case, and one in the centerboard itself. But since the commonly available bushings are shorter than the centerboard is thick, you end up putting two in there and trimming off whatever excess length you have from that.
DeleteRegarding the centerboard cap, I am of mixed opinion. Omitting it would be easier and provide an uninterrupted seat surface. Putting it in allows access to the top of the centerboard for inspection, clearing of jams if you ever get pebbles in there, and easier rigging of the downhaul line. I have heard a third option, which is to include a partial opening. Apparently splashing up through the back end of the cover can be an issue and cause a wet seat. Leaving the back 8 inches or so of the trunk permanently covered solves that, I guess. Installing a centerboard gasket at the bottom of the trunk would fix that, too. Haven't yet made this decision on my build, so stay tuned for that.
Thanks - Dave
Dave, I love the flared ends of the tubing. Is there a tool to do this or did you simply use the bolt for both sides? This is such a nice way to finish the CB case…I love it. Do you feel the 1/4" line is sufficient, even now with the added weight of the CB being 22 lb.?
ReplyDeleteBrent
Brent - I flared one end of the tubing before I inserted it, and I used a flaring tool from the plumbing section of Menards.
DeleteI had not had one of these before and I decided to get one for this job and potential future plumbing uses. You have to have free access to the end of the tubing, as it clamps on to the end. Here's a link to the one I got: http://www.menards.com/main/plumbing/plumbing-tools/expand-extract-bend/flaring/professional-flaring-tool/p-1339123-c-8604.htm
I think I could have used the bolt method for both ends after the tube was epoxied in place. If trying to use it with the tubing unsupported I expect the tubing would bend/crush/crease.
I think the 1/4" line is plenty strong, and it's a nice fit in the tube, and is the right size to fit the turning block and the other blocks and cam cleat at the pulling end of the line.