Keel Fairing

[Pterobyte]

I am re-fairing the keel on Pterobyte. I a new template from Computer Keels.

I am finding that my keel is built up with several layers of glass over the lead. Is the glass there just to build it up?

[darkstar32170]

The glass was really part of the fairing when the boat was originally built. On mine the glass over the lead extend up over the keel stub and forms a stronger joint that does not have a tendency to crack at the joint like I've seen on so many boats.

I would think that you will be able to do a good fairing job without removing any glass. The polyester resin used tends to shrink so if anything the keel would be smaller than spec.

[FlatlineE32]

Is the Computer Keel template there own design or a template of the original keel?

How far down on your keel does the glass go? I assume 8" below the bottom of the sump.

[Pterobyte]

My glass was already separated from what looks like a previous keel removal. The joint was filled with structural filler with no continuous strands, then faired over. I can fair it down and then lay fiber back back up extending the glass to the stub? the class is about 3/16 on both sides making the profile about 3/8 wider then it needs to be.

It sounds like the glass served a structural or stiffing purpose?

[darkstar32170]

I would think that the glass extending from over the stub down over the lead keel would help strengthen the joint between the keel and the stub. I've own "Dark Star" for over 10 years and there's never been any indication of exactly where the joint is located. This despite having run aground a couple times.

I had the opportunity of meet "peter ross" 2 weeks ago. He worked at Formula Yachts where the first 8 (or 7) hulls were built and described the operation as "down and dirty." Its apparent that there are wide variations between hulls so some may have been fabricated a little differently in this area. Mine includes some black (carbon?) fibers in the glass in the main bulkheads and adjacent hull (thanks Ben).

I can't tell how far the glass extends below the joint. I have some photos of the last couple year's work that I will try to post on my website this weekend. I can see fairing and original gelcoat on the keel in the photos after my last standing job. The keel is still very fair except for the forward part of the tip from the last grounding (gouged out some lead on that one). Before the boat goes in the water in the spring I will finish fairing the hull in the area immediately aft of the keel (there's always been a crease there and the previous owner says it was there when he owned the boat) and applying the barrier coat.

[FlatlineE32]

John Fries (musicman) is the one to talk to in regards to this. He had to rebuild a lot of this area on Remedy to stiffen the Keel. The fact that you mention the glass is already separated leads me to believe that you might have some flex happening.
There are also issues with the use of uni carbon in the sump without vacuum bagging and poor saturation of resin which results in delamination. I spent a big part of last winter reinforcing my sump and keel to keep the flex to a minimum. I glassed in some stringers to spread the load in the sump to minimize flex. It made a huge difference in my upwind performance.

[Pterobyte]

There are some uni black fibers exposed. I thought they might be black due to anaerobic bacteria from being wet. They may be carbon. It looks like I have to talk to John. I have his number, he didn't go down to Key West like all the A crowd did he?

[Pterobyte]

These black uni directional fibers are carbon.

[FlatlineE32]

Does anyone have the specs for the original keel templates? I remember seeing them on this site a long time ago, prior to the forum being established. I would rather go with the original specs instead of the universal templates you would get through Compukeel. Any suggestions would be great.

[Pterobyte]

I am re reading some of my previous post and input.

Ok, it has been a year since I re-did my keel. The glass on my keel ran over the lead all the way to the bottom. There was no section of the lead that was not covered in about 3/16 of cloth.

The bulk of the cloth was removed my keel as I faired it back to shape. I put no cloth over the joint of the lead to the keel box. The boat shows no signs of cracking at this joint and it is very very stiff now.

[FastCrab]

Somewhere, I found info on the keel size and section that said it is a NACA 65A010. I thought I found it here but can't seem to now, but it had a keel chord length of 4ft 6in, a bottom chord length of 27.6", and a vertical (span) of 4ft 10 in. Using these dimensions, I did a 3D analysis comparing the N65 with other sections. See attached.

[Intensity]

Well.... I am undertaking the chore of repairing the keel sump and fairing the Keel. Of course I'm not an expert, but in the amount of time I have spent on line investigating i believe I can handle the chore. Any advice on coming up with the keel templates would be greatly appreciated. This project has become rather large so anywhere I can save is gonna be awesome.


Thanks
Scotty Butcher
Intensity US25030

[FastCrab]

I need to do the same, have you done it yet? I have a CNC router and the knowledge & ability to make templates.

Rick Loheed
www.loheedtech.com

[Intensity]

Working on re-building the sump and then we will be fairing the keel. still a little ways off as we have a ton of projects going all at the same time.