Building Allie Kat
A Somes Sound 12 1/2
Right-side Up
How Much Does It Weigh Now?
I'm ready to turn the boat - it seems like a good time to figure out much she weighs at this stage of construction. The boat is presently supported at two points: The mast web frame and the station 12 mold. I lifted the aft end up and put a scale under the transom. With the boat supported at the mast web frame and now at the transom, the scale read 89.6 lbs. For the following calculation I assumed a uniform distribution of weight along the length of the boat, which isn't true – the boat is lighter in the ends. I think small errors introduced by this assumption offset.
Uniform Distributed Load = U lbs/in
Since the boat isn't moving (it is static), the sum of the forces will be zero. I'll use Moments to make the calculation.
The sum of the moments at the mast web frame equal zero
Moment Forward + Moment Aft + Moment Transom = 0
FM + AM + TM = 0
FM and TM are counterclockwise: defined as Positive
AM is clockwise and is Negative
FM = 1/2 * 64 in * U lbs/in * 64 in
AM = - 1/2 * 124 in * U lbs/in * 124 in
TM = 89.6 lbs * 124 in = 11,110 in-lbs
0 = FM + AM + TM
0 = (1/2 * 64 in * U lbs/in * 64 in) - (1/2 * 124 in * U lbs/in * 124 in) + (11,110 in-lbs)
0 = 2048 * U in-lbs – 7688 * U in-lbs + 11,110 in-lbs
0 = U lbs/in * ( 2048 – 7688 ) in-lbs + 11,110 in-lbs
U lbs/in * 5640 in-lbs = 11,110 in-lbs
U lbs/in = 11,110 / 5640 = 1.97 lbs/in (call it 2 pounds per inch)
Total weight is the Uniform Distributed Load (U) multiplied by the total length
Weight = 2 lbs/in * 188 in = 376 lbs
Moving day – Rolling the boat (It rained of course)
My wife and I had three couples come over for dinner and to help with the big event. With eight of us it felt a little crowded in my small work shop, but I was very glad for the help.
The primary task was to get the boat right side up and on the cradle, but just as large a job was getting the lead ballast keel out of the garden and also onto the cradle.
The cradle base has wheels on it so that I can roll the boat out of the garage for sanding. When I finished planking the boat and before painting the hull, I lowered the boat off of the building jig and onto the cradle base (but still upside down). Now I needed to:
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Lift the boat off the cradle base
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Roll the boat right side up
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Position the lead ballast keel on the cradle base and under the boat
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Lower the boat onto the ballast keel
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Support the hull so that it won't topple off the cradle
To lift the boat I used a chain fall hoist hooked onto a large eye-bolt that was thru-bolted a 2 x 8 board that I lag bolted spanning three ceiling joists. (I plan to use the same arrangement to lift the boat when it's complete so that I can roll the trailer under it.) The other end of the hoist hooked onto a nylon strap that looped through the inside of the centerboard trunk and around a beam under the boat. The beam was made up of a couple of 2 x 4s and spanned the width of the boat and pulled up against the sheer plank on each side at the center. The lift was easy for the chain fall – I put a painter's drop cloth on the hull to protect it from the chain as it ran through the hoist.
In the building instructions Brooks suggests a "short-handed" method for rolling the boat which I thought was very smart. I attached blocks to hooks in the ceiling over the forward and aft ends of the boat and ran lines in a loop under and around the hull. (The line is polyester double braid that will eventually become sail halyards – very strong and no stretch.) With the boat suspended in the loops, it easily rolled right side up. The line traveled through the pulley blocks during the roll so there was no friction – the hull was left unmarked.
With the boat suspended in the loops and right-side up, we rolled the cradle base out from under it and out into the rain to load the lead ballast on. Using an A-frame gantry that looks a lot like a child's swing-set and a second chain hoist we got the lead ballast out of the garden and onto my truck. Then after a short drive down the driveway, out of the truck and onto the cradle.
With the cradle and the lead in position under the boat, we used the chain fall hoist again to lower the boat onto the lead and the cradle. We put temporary bracing up to keep her secure and proceeded to celebrate a job well done with drinks and dinner.
I was super-pleased with how well the boat and the lead keel joined together. I think key to getting an accurate fit is making two templates. I started by making a template out of heavy plywood that followed the top of the lead keel – this template is on the boat side of the joint (call it a "Negative" template). Once I had the Negative template fitting tight against the lead I used it to make a Positive template that represented the shape of the lead. The Positive template then went to the boat where it was used to fine-tune the shape of the mating surfaces (keel filler and deadwood). The results were nearly perfect.
Sheer Clamps
For several months the sheer clamps had been sitting in the stairway that goes up to the room over the garage. They were constructed and stored before planking began. Installation was easy. We've all seen photos of a boat with the rail or the sheer clamp going on using about a hundred clamps to hold it for glue – it looks cool. I found that I only needed about 10 or 12 clamps. Screws plus the clamps did a good job of holding the sheer clamps in place.
The full size plans provide a curve that is the bottom of the deck camber. I made a plywood template for the curve and used it and a spoke shave to shape the top of the sheer clamp, getting it ready to receive the deck.
After the sheer clamps were in I scraped and sanded plank seams and did a general cleanup of the interior. A heat gun and a sharp scraper were essential.
Floors.
Installing the floors was one of the most difficult tasks to this point. It is physically hard because the round bottom of the boat is constantly pushing you toward the middle – so there's a struggle with gravity. And even though it's an open boat, this is a small space and there is a lot of bending over and squatting. But the biggest thing that made this task challenging is that there are 26 individual pieces that were cut and shaped, and then glued and screwed in place – often with multiple trips to the bench to make adjustments before installing and moving on.
The floors are laminated douglass fir and were constructed months ago on the building jig before planking. I started by cleaning gobs of epoxy and smoothing all four sides. They were labeled when I first put them together and I had to be careful to re-label them as I cleaned.
Before removing the boat from the building jig, I drew lines on the interior of the planking showing where each of the station molds were. I found that placing the floors on the lines didn't quite look right. Using a carpenter's square based on the centerboard trunk gave much better results. I think the molds must have moved a little during planking and were no longer perpendicular when I traced them to get the first set of lines.
I braced the floors in place from above with clamps that push, and drove screws thru the bottom of the boat from underneath.
After the floors were glued and screwed in place I began measuring, cutting and installing the "floor fillers" and the "trunk log cleats." These many parts follow the curve of the keelson and fit up against the centerboard trunk. They essentially double the size of the trunk logs. The finished assembly undoubtedly makes the center of the boat abundantly strong and stiff. I come from a long line of engineers and we have a saying in my family:
Anything worth engineering is worth over-engineering
I think both dad and granddad would have appreciated the sturdiness of this floor assembly.
Drilling for Keel Bolts
In the building instructions, John Brooks cautions that drilling lead "can be tricky." If the lead heats up the drill bit can bind and be permanently stuck in the hole – impossible to get out. This is a problem I did not want to face.
I had previously drilled a hole in the lead keel for the centerboard pivot pin. I found that the slow speed setting on my portable drill (the screw driving speed) worked great. Drilling for about twenty or thirty seconds with firm pressure made a quarter to half inch progress. Then pull the bit up and clean the lead out of the flutes, and then back in the hole for another twenty to thirty seconds. The drill bit never got hot, only slightly warm. I didn't use any lubricant – the bit was dry. Less than twenty minutes per each hole – there are 9 of them.
The aft most hole thru the keel goes in angling aft – I picked up the angle from the scaled drawings. The forward most hole was drawn to go under the mast step. I moved that hole forward about three inches to go in just forward of the mast web frame to avoid complications when I install the mast step.
There are three holes on either side of the trunk that penetrate thru the trunk log cleats and floor fillers. These holes angle in to follow the sloping sides of the lead keel. I built a jig to ensure that I had the right angle as I drilled each hole.
