J/30 Class Association Forums J/30 Forum The Boat, Sails and Equipment Putting Rhapsody's Keel on a diet

I decided to bite the bullet and template the keel this spring. I didn't realize just how fat the keel was. Below are two photos of work in process. I bought the Computer Keels class keel templates printed on Mylar and constructed the actual templates using mattte board and 1 x 2 lumber.

I borrowed Mark Rotsky's Bosch power planer, but unfortunately broke a belt about an hour after the only place in town that stocks the belts closed for the weekend. So, I now own a cheapo Makita power planer from Home Depot, and still owe Mark a new belt for his.

This is a 4 Ibuprofin job. My back is killing me and I'm only done planing the top 4 stations. The keel was very fat. I have carried away 5 bucketfulls of lead shavings.

I started by using a straight edge and grinding the trailing keel edge straight. The upper part by the keel joint had "grown" over the years where fairing cracks were routinely patched. The bottom edge on the other hand requires buiding up. The templates would not fit over the trailing edge until I planed both sides of the keel. Once the templates were fit over the keel, I found the leading edge required building up 1/4" to 1/2". I plan on attaching a fiberglass batten and will fill around it with fairing compound. The leading edge intersection with the bottom of the keel needs to be built up as there is a large gap (~1.5") missing that has probably been ground off over the years.

Below are photos of work in process. The templates for sections 1 through 4 now fit and the chord lines all intersect with the straight edge. I may shave off just a slight bit more so the finished profile fits the templates with the fairing compound.

Sounds like you are going to need a heavier crew ...
I will bring my templates up north to compare in April.

How many pounds on the rail to make up for 10 lbs shaved off the bottom of the keel?

Sounds like I picked the right weekend to go home for spring break!!!

Kidding Bill, you'll show Jeff and those Epiphany guys when summer rolls around. I'm back Sunday evening so feel free to requisition me for work whenever you please.

Ok - our weather hasn't cooperated this spring between the snow and cold weather. Today temps hit 50 degrees after being in the 30s last nite. Lead doesn't warm quickly. On Sunday afternoon with the temp a balmy 52 degrees I finally was able to start building up the stations with thickened epoxy. The day I planed the keel it was 60 degrees so I was able to cover the lead with neat epoxy to seal it.

The area is covered with wax paper and the line drawn on the paper so the template can be positioned in the correct spot when the line on the keel are covered with epoxy. The wax paper allows a squeegee and roller to be used to move the thickened epoxy around. This makes it easy to match the contour to the templates.



Below you can see the 1st and 4th template stations faired. You can also see where I epoxied a batten on the front edge of the keel to extend it forward, since the keel was short fore-aft dimension.


Here is a view of the stbd side with the top 4 stations built up. Once the thickened epoxy cures, the wax paper will be peeled off and the contour checked with the templates. Minor sanding and filling if needed will be done to make the fit perfect. The chord positions will be marked and a straight edge used to make sure the chord lines line up flat across the various stations. Once they are verified as straight, thickened epoxy will be spread between the stations using wax paper and a roller / straight edge across the high spots built up. I'll do the keel bottom (station 5) after the rest of the keel is done. I need to raise the boat off the keel and don't want to leave it that way for an extended time.



I'd like to finish this next weekend weather permitting because I'm headed to Antiugua the week after that with some friends to charter a boat. I'd like to be able to have the boat ready to launch by the end of April.

Very clever doing only the measurement stations to start. Once they're spot on, I suppose you fill in between and fair with a straight edge?

Yes - that's the plan. This should make the final long-board sanding a minor effort.

Did you find that the bottom template station was below the bottom of the keel?

The front point of that station is for sure. I'm sure over time the leading edge corner has been rounded off as that's where the boat hits when grounded..... I built up the front by extending the line with the batten by about 1.25" and filling the void with thickened epoxy. The aft end of the keel looks ok. Since the keel makes a pretty good dent in the block it is sitting on, it is difficult to tell how the bottom edge is until I lift the boat off the keel block.

That is the way I did a j24 keel from scratch. The technique works well, and it actually measured in!

I did this to Evelyn a few years ago, but i have always wondered what the bottom of the keel should look like. Is it flat or is it a "v" like the j-24's. I found that my keel was aft by about 3/4" and the chord length was short by about the same. it is not a fun job, but to be competitive it has to be done.

Luke - according to the specs listed at the bottom of the J/30 Class rules, there is a note that reads tip rounded to a centerline depth of 20mm maximum below Section V. To me that sounds like a curve with a radius just over 0.75". I'm thinking of cutting a section of PVC pipe lengthwise, lining it with release cloth, then filling with thickened epoxy to provide a uniform shape for bonding to the keel bottom.

Were there ever keels built close to templates? If so, they would have more ballast then all of our short shallow (pre-templating) keels, wouldn't they? If that is the case, would it be legal to add depth to the keel (obviously only up to template limits) using a substance with some weight?

Steve - I see no restriction that prevents using lead as a filler. Good luck getting someone to work with hot lead. This is the way that auto body repairs were done before Bondo was invented....

Lead powder or lead wool chopped could be two alternatives used as "filler" in epoxy?

So OK ... the weather up here actually is getting close to 60 during the day ... at least one day a week with sun. Visited Bill who is trying to catch up on his keel work before the summer starts.

Bill,

Lookin good! Though I guess if you were working that you missed your intended launch date of last weekend. If it's going into the water before May 18th then let me know and I'll do my best to come up and sail her down with you.

Wes

Rhapsody should go in the travel lift sling late Friday so I can finish the keel bottom and paint Saturday. Boat will launch on Monday 9 May, possibly Sunday if BLM wants to.

Two more images below. All the fairing work was done using West Systems thickened with a combo of colloidal silica and fine fairing compound. It was a pain to sand. I'm going to apply a skim coat of stuff easier to sand to fill minor surface imperfections, then start barrier coating. The bottom section will be done when the boat goes in the sling Friday afternoon, and will launch Sunday or Monday.

The upper leading edge needed to be extended about 1/2" near the top as even with the batten epoxied on, the upper leading edge was not parallel with the rest of the keel leading edge.

Bill-

Nice work! I did this (with help) on another 30 10 yrs ago. That keel was asymetrical - fat on one side mid-chord to the trailing edge and "hollow" on the other aft and very fat forward.

Power planer is indeed the ticket. We used tooling to create template "ridges" with yellow-dyed west filler. Once each was done, we too were able to just drag a bunch of thickened filler across the new template stations (like screeding concrete) and it worked quite well.

It was a long (and physically taxing) project but well worth it. You'll notice a difference (i.e. more consistent on each tack) which always required funky tuning to deal with before. Boat also felt less sticky in the water (but that might have also had to do with burnishing to 1200 too... ;-)

Looks great AND you'll be very happy you did it after you get over the back pain!

Cheers,
Jeff

BTW - one tip if you haven't considered it is an airboard for longboarding a little more efficiently. They're used in bodyshops. Those can really cut through the harder west filler/epoxy materials and then you can use 410 (if I recall correctly) for last skin and then a standard manual long board.

Follow with barrier coat (we used interprotect if memory serves), bottom paint, burnish, and splash! Boy - that sure makes it sound easier and faster than it actually is, huh?

Cheers, Jeff

Boat comes out tomorrow to strip, fair the rough spots, barrier coat and anti-fouling (Pettit Premium Performance). Unfortunately I only have 4-5 full days so I am going to have to go at it like a madman. I am going to throw the templates on and pray that the keel is reasonable otherwise I'll need to come back to it another time.

I am scared... someone hold me.

When did you get the templates? I would drive up to see that.
I am sure I have to do mine. I dive the boat all the time and refaired the keel 3 years ago but did not template. I know there is more speed there. And now that we are all coming together I feel I need that edge

The work is done. Finished the final wet sanding and burnishing late Saturday and Rhapsody was launched. Pictures below are Rhapsody going in the water, and friends Mike & Cheryl who helped with burnishing and hull waxing.

The maiden voyage from the winter storage spot in Fall River, MA to my slip in Newport was done Sunday morning. The crew included Vic Farmer (Vee Jay) and friends Mike & Cheryl. Winds were out of the north 10-15, and perfect for a spinnaker run the entire way. Now I need to work down the items on my list that were not in the way for launching...

So OK ... invited Bill over to look at #526 a couple of weeks ago and he tried to sell me on me doing a complete template and a shaving of lead.

But I didn't go for that two weeks before the boat was due in water.

We moved on to "plan B" which was to make a really straight leading edge and kick it out to where the specs indicated it should meet the hull ... which was just about an inch short... and over three inches rounded off at bottom.

photos are prior to final sand. I am happy with Plan B, with thanks to Bill. That leading edge looks mean.

thinking about Waterline in a recent thread ... I ran across this recent Sailing Anarchy tread on J24 keel work. On the subject of keel work

I'm just wondering as I do when we talk about the perfect specs, is what the J30 spec'd keel template was supposed to do best, based on what they knew 30 years ago ... upwind, downwind, beam ... and what the ideal wind and water conditions this ideal keel is supposed to have?

I'm now thinking the only place a faired keel is worth it ... is when every other boat in the fleet has the same shape. Otherwise some are going to be faster upwind in light air, faster upwind in heavy air, etc etc.

when you read experts talking about what design is "perfect" there seem to be a lot of very exact conditions when "perfect" applies.

one of the comments in the j24 thread talked about the most important thing being a perfectly smooth surface and nicely shaped surface.

Vic,

It's safe to say that the keel shape I had on Rhapsody and you had on Vee Jay were not fast or optimal. Pointing ability is noticeably better since templating the keel. A smooth bottom is better all around no matter what the keel shape is.

I will second what Bill is saying. There is no question that the keel fairing to templates helped our performance both upwind and down. Well worth the effort!

I have LIVED the J-24 fairing experience. I was forced to do it DIY as my boat was destroyed by Andrew, and I ended up with a J-World boat that was painted with bottom paint, and the keel was just as it came out of the factory. Some shape on one side, AWFUL on the other. There are also articles written on the subject of keel fairing. I am NOT one of the proponents of moving the keel. (We didn't have the time either) In the J-24 at that time, the minimum thickness table of offsets in the class rules resulted in a decent shape. I expect that the J-30 is similar. What you do need is a comfort level working with battens to loft a fair curve. If you are not comfortable with lofting curves, I do not recommend a DIY attempt to fair the keel. Take your time.

While I am sure my keel wasn't pretty, it did measure in, and it was very fast.

The reassembly of hull #62 is moving along. Repairs are all done and it's down to fairing and painting and such. Time to do the keel.

I've been making templates and carefully measuring. I knew it was short, fat and shallow. Surprised by how much off it is, especially the shallow part. There's almost 1.5 inches missing on the bottom. Looks like that's the way it came from the factory. Section V is under the bottom of the keel.

So...anyone with experience adding depth to the keel on the bottom? What material? The boat sits on this each winter. Should I get a "shoe" made or just epoxy with high density filler and fibers?

All the boats I know of that have faired their keels ( including mine) had a shallow depth (section 5 is off the keel). I think all left their keels short-it is too hard to make a durable shoe that won't fall off or be damaged when the boat is on the hard or scrapes bottom. If anyone has extended the keel depth, I'd love to hear how they did it. It seems to me that adding lead for the shoe to match the templated shape could really help righting moment and should be class legal...

For Rhapsody, I mixed thickened epoxy, made a "hot dog" shaped tube with it and taped it in place with wax paper at the bottom of the keel. I allowed this to harden, then shaped it and faired with the templates.

I don't think lead is worth it. Like 12 pounds in my case and worth something like 4 pounds of rail meat. Give a six pack to the crew and get more effect.

The foil simulator gives a bit more lift with a 1.5 inch extension, about 3 tenths percent. Not much but it's more than it gives you for shaving the aft sections to class minimum.

Seems the bluntness of my leading edge is a bigger deal. More likely to stall at low speed.

By the way...after some more measuring and number crunching, our class minimum keel section is an NACA 0012 with about 85% of the trailing edge trimmed off.

My leading edge is much more blunt than an 0012...much. The theory suggest fixing this should improve performance coming out of tacks, powering up at the line and managing light air chop. Might point better but really shouldn't make much difference when you're in the groove. Likely pinches better. Seems like the consensus of the actual benefits of of fairing to templates.

You may have the math to back it up (I know I don't!), but it seems to me that twelve pounds of additional weight at the extreme bottom tip of the keel would have more of an impact on righting moment than 4 pounds on the rail. Both the hiking position and the bottom of the keel are about the same distance from the axis of rotation (about 5'+ or -). Seems to me if you go to the trouble of adding the depth, mixing in a generous quantity of lead shot would be well worth it.

The thinner leading edge and the longer chord length make a significant performance difference upwind. I find I point better, accelerate a bit faster, and have a more stable groove in lighter air.

Imagine a vertical plane that passes fore and aft through the center of flotation. The righting force of a weight is proportional to the distance it is from that plane. Unless you got her WAY over, the rail is further out from that plane than the tip of the keel. Rail meat is much more effective than keel weight if you sail her flat. On the other hand, if your worried about knock downs weight in the keel tip is the best place for it.

Math aside, I'd do the whole thing in lead if I could figure out a way that wouldn't cost a fortune and I was sure wouldn't fall off. Expect I'll end up doing something like Bill.

That makes sense! Thanks for the explanation.