20+ Footer - Building in Hawaii

[Jim Donovan]

Tradition in this shed is that boat names begin with the letter "T".
My vote is to name it "Twenty"

That's definitely the moon at the spreader tip; bow's pointing about 80 degrees true

 

[Jim Donovan]

Checked the rake yesterday and currently at 3.5 degrees.
I'll move the step 15mm forward (next set of holes) and get it to my "designed" 4 degrees. Bill's back at his loft building a prototype jib out of some cheap sail cloth so we can hoist it, check the clew board location and maximize the roach. Figured this was way cheaper than re-cutting a real sail.

I'll also get the boom on the mast to get a real life feel for how much clearance we're dealing with.

 

[Jim Donovan]

Waited til 10AM to go out and adjust mast step and set up the boom and found the deck glistening with a thin covering of very slick frost! It's 37 F (3C) and blowing about 18 knots out of the south, so wind chill at 26F (-3C)

Wheeled the boat into this mornings bright sunshine and wind; hopefully that'll melt/dry things. Good thing about cold air is the humidity is @ 55%.

Give it an hour or two and hopefully back into the lee of the shed and some sunshine.

 

[Jim Donovan]

"Warmed" up (39 F) a bit and went to move the mast base 15mm forward. Had to "bail" the boat first ; just drop the ice down the keel slot . . . "puddle" under the boat at the end of today.

 

[Jim Donovan]

Boom went on easily. Vang bottoms out with the boom about 12" off the cockpit, purchase strop lengths seem good. Reasonable clearance and visibility under the boom. There's many 3" more droop to the boom than design in this photo.

 

[Varan]

That is really a fine looking boat. Well done.

 

[JulianB]

Got to tell you I really liked this shot

Your sky is so much prettier than ours at the moment.
But it's been so wet here, no chance in hell of a bush fire.
The smoke makes for amazing sunsets.

But the boat is looking good also. Congratulations in conditions I would not venture outside in.

Can't say I'm up for the ice, warm water sailor, and by warm 17-24c.

 

[Will1073]

Congratulations Jim, boat looks fantastic

 

[Jim Donovan]

Hoisted the test jib yesterday; when Bill (Vermont Sailing Partners) left his loft in Burlington he noticed light winds, ideal for this trial. I had warned Bill the red shed is in the windiest place in Vermont, and sure enough, when he arrived it was blowing a steady 18 gusting and over 20 from the North.

I had tucked the boat in the lee of the shed and we hoisted the jib in the swirling wake of the shed. The wind direction would change from downwind to upwind on starboard & port every 5 seconds.

We backed the boat away from the shed to get out of the swirl, and finally got onto a reasonable port tack. We couldn't poke the bow out into the full breeze or we would have certainly flipped the boat and trailer (no bulb on the boat yet).

It was a very "active" situation with no chance to stand back and take photos

The test sail was a really simple thing that only took 3 hours to build and showed us several things; luff length was perfect, leech could be 2" longer, 3" of foot round will get the sail right down on the deck. The cost of this sail was way more economic than a recut on a real sail.

Biggest question was how much roach can we put on the leech and have the upper batten tack past the mast. The wind swirl definitely confirmed this without about 25 tacks in 2 minutes.

 

[Jim Donovan]

Back at it today; added "capping laminate" onto top and bottom of keel fin. You may remember that I have bronze tapping plates glued into the fin ends with a G-10 plate over. Not confident that the edge glue joint between the G-10 and fin laminate will be enough, so added a covering laminate to be sure.

 

[Jim Donovan]

The difficult part is sorting out how NOT to fill the tapped bolt holes with glue.
I had bolts used previously to fill the bolt holes when I glued the fin together, and modified those for this laminate. First step was to cut the heads off the bolts, and then drill a hole to accommodate an "easy-out" extraction tool.



Drew some guide lines on the fin so I can find these bolts later

 

[Jim Donovan]

On the upper 1/2" bolts I cut a slot to allow me the use a screw driver to insert the head-less bolts so they were flush with the G-10 plate. Crammed some mold release wax into the slots to prevent the epoxy from filling everything. Sanded and rounded the sharp edges for the laminate.

 

[Jim Donovan]

Capping laminate added; the upper laminate has to lift the entire boat, and I was able to lap a couple layers of Unis and a DB down 6" onto the fin sides; this part of the fin is inside the keel box.




The lower part only needs to hang onto the bulb, with about 2" of fin available for that cap laminate.



CRAZY weather today; almost 50 degrees today melting off all the snow.
Supposed to drop to 12 tonight which will make outdoors a giant skating rink.

Tomorrow I'll stick the fin into the oven and cook this laminate.

 

[Jim Donovan]

Merry Christmas/Happy Holidays/Happy New Year!

It's really great when things worked out as planned . . .
After "inviting" the keel fin inside our home for a few days so the resin would cure, I was able to dig into the capping laminates and extract the bolts filling the threaded bolt holes.

Guide lines worked out perfectly and every hole revealed the inserted bolt.
For the lower bulb bolts, the bolt extractor worked perfectly.


3 x 3/8" 316 St Stl rods thread into the bronze tapping plate and then go vertically through the bulb with nuts & washers recessed on the bulb bottom.



Spent about 2 hours chiseling the bulb recess a bit wider and deeper. The good thing about the cool shed is there's almost no sweat involved.

 

[Jim Donovan]

There are 4 x 1/2" diameter bolts tapped into the top of the keel.
Again the guide lines worked perfectly and the slots cut into the beheaded bolts made the extraction super easy.




I've laminated and just need to cut out and glue the fin bolting plate to the top of the fin.
I've also built a carbon/core panel that will become the "spacer" that fills the rectangular keel box.
More to come soon . . .

 

[Jim Donovan]

Woke up at 3AM thinking about exactly how to fit the fin to the bulb, and then got out of bed 45 minutes later to draw the solution.

Few things in play here:

• I want to be able to remove the bulb so I can pull the fin out of the boat if needed; the fin can only be removed upwards.
• The lower end of the fin needs to be tapered so it draws up tight into the bulb when the bolts are tightened.
• The tapered "thing" at the bottom of the fin needs to fit out the slot cut in the hull that's a reasonably tight fit on the fin at the hull.

Designed a wooden plug that I'll pot into the existing recess with high density filler. Eventually this will be the shape of the fin that fits into the bulb.

This plug will also serve as a drill guide for boring the holes for the threaded rods (bulb bolts).

Cut, glued, sanded and covered the plug with release film, then stuck it in the bulb.





After potting the plug into the bulb, I'll fix any voids, smooth the recess, and wax - wax -wax it.

I'll set the fin into this recess, using the laser level to get everything perfect, then pot the fin into the recess. That should be as "perfect" a fit as possible.

There was quite a lot more activity getting the bulb (Egyptian pyramid style) moved to the chain lift and then dropping it into the mold I built to mold the upper half of the bulb plug. With the bulb securely held in the mold I can easily level the mold to level the bulb.

BTW I'll use this mold on the trailer to cradle the bulb.

 

[WCB]

Woke up at 3AM thinking about exactly how to fit the fin to the bulb, and then got out of bed 45 minutes later to draw the solution.

Few things in play here:

• I want to be able to remove the bulb so I can pull the fin out of the boat if needed; the fin can only be removed upwards.
• The lower end of the fin needs to be tapered so it draws up tight into the bulb when the bolts are tightened.
• The tapered "thing" at the bottom of the fin needs to fit out the slot cut in the hull that's a reasonably tight fit on the fin at the hull.

Designed a wooden plug that I'll pot into the existing recess with high density filler. Eventually this will be the shape of the fin that fits into the bulb.

This plug will also serve as a drill guide for boring the holes for the threaded rods (bulb bolts).

Cut, glued, sanded and covered the plug with release film, then stuck it in the bulb.

View attachment 563445

View attachment 563446

After potting the plug into the bulb, I'll fix any voids, smooth the recess, and wax - wax -wax it.

I'll set the fin into this recess, using the laser level to get everything perfect, then pot the fin into the recess. That should be as "perfect" a fit as possible.

There was quite a lot more activity getting the bulb (Egyptian pyramid style) moved to the chain lift and then dropping it into the mold I built to mold the upper half of the bulb plug. With the bulb securely held in the mold I can easily level the mold to level the bulb.

BTW I'll use this mold on the trailer to cradle the bulb.

Out of curiosity, why didn't you go with a "melges" style keel fin with an aluminum plate on the top that can be removed to slide the fin out?

 

[Jim Donovan]

Out of curiosity, why didn't you go with a "melges" style keel fin with an aluminum plate on the top that can be removed to slide the fin out?

I've always wanted the ability to remove the bulb to allow easier modification of the fin and/or bulb, so no need to drop the fin through the bottom.

Thinking we'll want to shave some weight off this bulb after we sail the boat a while. Although we've found the GP26 likes as much stability as it can get; the keels were cast with a void to get to GP Class bulb weight, and most of the boats have filled this void with lead. The Twenty is a smaller and more powered up version of the 26.

Interesting discussion over at the 89er thread re: bulb weight. Where it's absolutely correct that the bulb doesn't add much stability at low heel angles, there is a significant contribution to stability at 20+ degree heel angles. Without racks and/or trapezes, it's pretty hard to keep a boat flat in higher wind speeds all the time. So I've developed this boat to have the ability to heel as much as 25+ degrees without any "drama". You can keep pushing the boat as hard as possible, all the time. Maybe that's important to me because I grew up sailing in San Francisco?

And the heavy bulb makes broach recovery happen in seconds, not minutes, or worse.
Seen those "keel boats" with the crew hopping out on the keel fin, or sitting on the hull of a turtled keel boat. You can do all that without a bulb.

 

[JulianB]

I've always wanted the ability to remove the bulb to allow easier modification of the fin and/or bulb, so no need to drop the fin through the bottom.

Thinking we'll want to shave some weight off this bulb after we sail the boat a while. Although we've found the GP26 likes as much stability as it can get; the keels were cast with a void to get to GP Class bulb weight, and most of the boats have filled this void with lead. The Twenty is a smaller and more powered up version of the 26.

Interesting discussion over at the 89er thread re: bulb weight. Where it's absolutely correct that the bulb doesn't add much stability at low heel angles, there is a significant contribution to stability at 20+ degree heel angles. Without racks and/or trapezes, it's pretty hard to keep a boat flat in higher wind speeds all the time. So I've developed this boat to have the ability to heel as much as 25+ degrees without any "drama". You can keep pushing the boat as hard as possible, all the time. Maybe that's important to me because I grew up sailing in San Francisco?

And the heavy bulb makes broach recovery happen in seconds, not minutes, or worse.
Seen those "keel boats" with the crew hopping out on the keel fin, or sitting on the hull of a turtled keel boat. You can do all that without a bulb.

Hi Jim, doubt you need a confidence booster but I have done virtually the same thing, and the original SKUDs also. 2 x M10 CSK MT up from underneath and being able to pull the fin out is really nice. We plan on trailering the boat with the fin out. jB

 

[guerdon]

Jim, thanks for the postings. She is a gem.