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Showing posts from February, 2019

Corbie 5 Fin Box Construction and Installation

Yikes... I'm really in uncharted waters here. Not only is this my first IOM, but it's the first part of the build where I've really been on my own to figure it out. The pros who have been helping me simply buy theirs pre-made and install it. 

Did I do that? No, of course not. I bought a fin and bulb and that's it. Pay $140USD or more for a fiberglass fin box? How hard could it be...?

Well, I'm not done yet, but so far I think I made the right decision. No, it doesn't look as nice as the pre-made ones... clearly! But it perfectly fits my fin and I made it myself and it was cheap and it should work and I don't care what else you say!

Here's how it looks tonight... 



Here's what I did.

First, after carefully mounting the fin to the bulb (see previous post), I was then able to carefully measure and cut my fin using my laser cut fin box template. I cut it almost perfectly using my tablesaw which made an extremely clean cut.

Then I taped up the fin.

Here…

Corbie 5 IOM Fin and Bulb Alignment

I've been working on a number of different things on my Corbie 5 IOM this past week. This post is on how I aligned and fixed the fin and bulb to each other.

First I used my IOM Alignment and Measuring jig. It worked well! See earlier posts for more info.


I spent a lot of time lining everything up as best I could. The Corbie 5 manual says to have the front of the fin at 493mm from the stern, the fin raked so that the base is 6mm aft of the top, and for the center of balance of the bulb to be 10mm aft of the leading edge of the base of the fin.

I then worked on the bulb. It weighed well over 2500g when it arrived, and I had to remove a lot of weight. First I had to hog out the channel so that the fin would fit.


I used my drill press to hog out much of it, and then my Dremel tool to remove the rest.

I also drilled out the mounting holes. This bulb came with a large brass insert that had a 1/2" base and a 5/16" sleeve. I had to use two different bits to get the holes to wor…

IOM Alignment and Measuring Jig (UPDATED)

I need to start to consider how I'll mount the fin and bulb, and get it all straight, so I made a 3D modeled alignment jig:



Ian Dundas in Scottland sent me pictures of his setup. I just bought a laser level too! He does amazing work and has been a great help in this project so far.




There is also another jig featured on page 14 of the winter 2008 Canadian Radio Yacht Association (CRYA) newsletter that features one. It's by Lawire Neish. Read it here.

I took both those designs and made my own version that features sliding cradles for the hull, a fixed waterline sight, proper depth to cradles for the bulb, etc... Most of the parts can be laser cut, and the two end pieces and the base can easily be cut on a tablesaw.

It has fixed waterline sights that are 420mm above the top edges of the bulb sliders in the base. The fore and aft cradles can be slid up and down to adjust the waterline of the hull. You'll see that the overall interior length is 1003mm to accommodate the aft…

Corbie 5 Hull off of the Building Jig!

Big day today... I cut the Corbie 5 IOM hull off of the alignment jig! Phew...

First I sanded the third coat of epoxy that I added yesterday. Then I used my waterline marking jig to mark the waterline. The waterline should be perfectly horizontal if you've used the frames properly. The manual indicates that it start 15mm aft of the back of the bumper, and run to 3mm forward of the stern. My tool holds a pen at an angle, and when it gets to flat areas like the stern it doesn't do as well as on more vertical surfaces. So I started at 15mm from the bow frame and ran it aft. It ended up about 14mm fwd of the stern, but that is due to my jig. I'll adjust slightly before I paint it on.

In this first picture you can see how it doesn't work as well. Yes, the cap is on... I'm not actually marking it yet. 


Here you can see where it works much better and more accurately.


Then it was time to remove the hull!

TA DA!

This is after I cleaned up the insides. I didn't sand it …

Corbie 5 Experiments

Lots of various projects going on the Corbie 5 IOM RC sailboat this week. Over the past few days I've worked on the hull, the foredeck, and the aft deck. Here's what I've done:

On the hull, I've put my second coat of epoxy on the hull, sanded it off, and just now added the third coat.


Tomorrow I will lightly sand it off and then mark the waterline with this...


After that I will leave it lightly sanded and will eventually add a few light coats of varnish for UV protection. That varnish will be sanded and polished in the end. Won't be as glossy as unsanded epoxy or varnish, but will be very smooth and have a very fair surface.

I realize that doing it this way will probably add significant weight, but again... my sailing skills are so poor that it really doesn't matter!

Tomorrow I get to also remove the hull from the frames!

I have also worked on my aft deck. It's made from 1/32" (.9mm) ply with two reinforcements around the underside of the openings, als…

Corbie 5 IOM fiberglassed

We've had a lot of snow in Seattle, which is pretty rare, but it's allowed me to work on the Corbie 5 IOM.

Last night I finished the planking. This morning I sanded and shaped the hull.




Then I fiberglassed it with 1.4 oz. cloth.


Here's how it looks now.




I'll trim the excess cloth in about 3-4 hours when it reaches the "green" stage. It cuts very easily with a hobby knife at that point.

Will let it cure, and then tomorrow I'll lightly sand it and then add a second coat of epoxy.

Looks OK. The cedar is really nice and dark. But my planking... Gawd. Even my keelson plank isn't perfectly straight.

I'm going to continue to make this hull, but probably as a practice one. I'll use it as a learning experiment, especially for the planking, the keel box area, and the foredeck. After that I may set it aside and make a better one if I have the energy for it!



Aloha!




Corbie 5 Updated Frames and Alignment Jig

The 3D model and subsequent laser cut frames have been working beautifully so far on my Corbie 5 IOM build.

Every plank is meeting every frame.

That said, there were a few things that I could tweak and improve. The main one was the rubber band hooks below the frames. They worked well as originally designed but will get in the way during sanding. They also could have been tucked-in more toward the center-line.

I also filled in the frames. They used to be hollow in the center, but I found that they tended to twist or bend too easily. Having them solid should make them stiffer and stay better aligned. In doing so, I'm giving up a small bit of convenience because at times it's nice to wrap a rubber band around the frame and back down to the hook, but this can usually easily be done another way. 

This is how it looks now:



I also extended the small steps that the gunwale plank sits on. They aligned my gunwale plank perfectly but were a touch too small. One plank slipped off and had…

Corbie 5 IOM Planking, Part 4

It's a snow day! We only get a day or three of snow here in Seattle each year, but it completely shuts down the entire city. Way too many steep hills here.


So it was a good day to epoxy down more planks. In the past week I also epoxied down the keelson plank. I'm going to make this hull work, but it's not going to be pretty!

Here's where I'm at now... closing in on the keelson.




The bow is by far the most challenging. It's nearly impossible to get the very front of the planks to twist into place. I've got strong clamps and tons of down-pressure from rubber bands. I've even wedged in some bits of scrap to try to further leverage down the planks, but just can't get them to twist the last little bit.

The outside will easily sand down to form the proper shape, but I'll most likely have very visible openings between the planks. Sigh...


Might be able to finish planking in the next week, but it'll be one plank at a time from here on out. Then it'…

Corbie 5 IOM Planking, Part 3

Planking continues. I'm awful at it.

But I'm getting better. Still terrible, but better than when I started. And yes, I'm still using the stationary sander instead of the planer that the pros suggest. I just can't get it adjusted well enough to work for me.

My plank making has improved though. I'm now ganging several planks together and sanding them as one. It's working well. My most recent attempt was six planks ganged together with clips.




Here's my progress so far. Don't look too closely or you'll laugh. But when sanded out and glassed it'll look better. Only the pros will notice, and to them the rookie planking will be obvious, but to most people it will look fine.

The building jig and clips I made for each frame are working really well! Much better than my actual planking. 



You can be very creative with the rubber bands to put pressure wherever you wish. It really works well.



Will probably need to consider doing the keelson plank soon.

More…