My new boat

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Shu
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Re: My new boat

Post by Shu » Fri Dec 09, 2011 11:49 pm

I was able to unscrew the #10 machine screw out of the still somewhat green epoxy the next morning. Then cleaned out the hole with the 3/16" drill bit.
This was followed by fairing in the washers w/ thickened epoxy microballoon mixture. It took two layers, sanding after each layer to provide a sufficiently fair surface for a layer of carbon cloth to finish it up. The cloth was cut at 45/45 to help it conform more easily. To fill in the remiaining small flaws, I painted the cassette with thickened epoxy prior to applying the cloth. While laying up the cloth, I poked the cloth into the 3/16" hole a bit, leaving a dimple to find later. After curing, I found the dimple and once again drilled out the 3/16" hole. Then, using the 1/2" counterbore Chris Johnson lent me, I drilled out the hole for the pin. Everything fits together very snugly. A little trimming of the aft edge at the bottom to allow room for the rudder gudgeon, and it will be ready to attach to the boat.
Attachments
I-14 11-6-11 056.jpg
G10 washers faired into cassette with epoxy micro-balloon mixture. Ready for final layer of carbon cloth
I-14 11-6-11 061.jpg
I used a 316 stainless 1/2" shoulder bolt with a 1-3/4" length to shoulder for the pin. The holes and pin diameters were carefully selected to provide a rattle-free fit (about .004" difference in diameters). The bolt, nut and washers were all 316 ss, which resists crevice corrosion better than 18-8 or 304 ss.
I-14 11-6-11 063.jpg
Opposite side. The shoulder bolt uses a 3/8" nut
Steve Shumaker
USA 1183

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Shu
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Re: My new boat

Post by Shu » Tue Dec 13, 2011 3:23 pm

The hole has been cut into the top forward corner of the cassette and the actuator plates cut from G10. Taping the two plates together for drilling the pin holes and shaping helps. I even dropped the pins in each hole to further align the plates prior to drilling subsequent holes. Sheaves on the two forward pins serve for the bungee attachment and the control line. Ready to glue to the boat.
Attachments
I-14 11-6-11 067.jpg
Upwind lifting mode
I-14 11-6-11 064.jpg
Downwind safety mode
Steve Shumaker
USA 1183

Northshore Pirate
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Re: My new boat

Post by Northshore Pirate » Fri Dec 16, 2011 5:18 pm

Hi:

Do you have an idea of how much carbon/weights would be needed to build the casset?

Ed
US1112

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Shu
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Re: My new boat

Post by Shu » Mon Dec 19, 2011 2:46 am

Unfortunately, I cut it out of leftover cloth, and I didn't keep track of the amount. Assuming some excess to cut off, I would think 4 yards of 50" or 63" wide 5.8oz (200gm) carbon cloth should be enough. You'll need maybe another half yard to tab it to the boat as well. The twill-weave cloth is supposed to conform to shapes better than regular cloth.
Steve Shumaker
USA 1183

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Shu
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Re: My new boat

Post by Shu » Thu Dec 22, 2011 6:36 pm

Glued the cassette to the boat last evening. 1st step was to bevel the back end of the gantry for the angle of the cassette. Then I set up a jig to hold it in place while the glue cured. I attached the jig to the UHMW mold, using plywood as a shim. This allowed me to true up the orientation of the cassette based on the inside configuration. After curing overnight I removed the jig and added epoxy fillets all around. When the fillets are cured enough to be firm, I'll fit in some carbon cloth tabbing wherever I can. As usual, I use epoxy thickened with colloidal silica for the glue and fillets.
Attachments
I-14 842.jpg
The jig is attached to the UHMW mold. The 1x2 clamped to the starboard side was needed to flatten a slight curvature that had developed in the UHMW.
I-14 847.jpg
The jig set up
I-14 852.jpg
The glue joint. Not very strong, but enough to hold the cassette in place for future reinforcement.
I-14 854.jpg
Thickened epoxy fillets added
Steve Shumaker
USA 1183

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Shu
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Re: My new boat

Post by Shu » Sun Jan 01, 2012 4:00 am

After spending a lot of time fussing with a rasp to shape the gantry side panels where they contact the cassette, I finally glued one of the gantry side panels on today.
Attachments
I-14 863.jpg
I used tape to hold it in place while the thickened epoxy cures
I-14 859.jpg
Steve Shumaker
USA 1183

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Re: My new boat

Post by Shu » Tue Jan 03, 2012 3:29 am

Both gantry side panels on now. I've added generous thickened epoxy fillets to increase the glue area. These will all have carbon cloth tabbing to further strengthen the assembly. The weakest joint is between the bottom and side panels with only the 1/8" thick edge of the bottom panel glued to the side panel. Therefore, this joint is reinforced with 3 layers of carbon cloth. The weave is oriented at 45/45, since most of the stress on this joint will be shear.
Attachments
I-14 868.jpg
Both side panels on now
I-14 867.jpg
Generous thickened epoxy fillets. In the foreground, I'm reinforcing the aft end of the kick bar, as it will serve as the anchor point for the foil actuator.
I-14 869.jpg
The bottom edge of the side panel was previously routed with a 1/2" round-over bit to make a nice radius for the carbon reinforcement
I-14 873.jpg
Three layers of carbon cloth added to reinforce the joint between the bottom and side panels. As always, the UHMW cassette mold is kept in place to keep the cassette from warping as the epoxy cures.
Steve Shumaker
USA 1183

Hendo
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Re: My new boat

Post by Hendo » Tue Jan 03, 2012 5:07 am

Steve,
We split the top of the cassette from the side bars on the B-6 in a Massive puff at the Gorge top mark! this summer.
this is now tied together with uni's over the top and down on the sides, with 4 or 5 layers of 45+/- to hold it all together.
Massive loads , and how about the top of your panels ? a uni and a 45 cover would keep the things from breaking when they get kicked.
cheers, Keep up the good work!
Kris H.

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Shu
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Re: My new boat

Post by Shu » Tue Jan 03, 2012 5:54 am

Thanks for the heads up Kris. I was thinking of a couple of unis on the inside and outside face for the top bars. Good idea about the 45/45 cover. For the top of the cassette I was going to fill in the triangular spaces between the top bars and cassette with some carbon plate, then cover the whole top area with 45/45 cloth wrapped down the sides. Based on your experience, I think I'll wrap some carbon tows over the top as well (personally, I find tows easier to work with in these convoluted places).

Massive loads! This seems to be an area where we are all still experimenting with what will survive the loads. Really difficult to quantify. Based on the theoretical lift of the foils, the loads are pretty big, but should be manageable. Experience shows otherwise though. People seem to break pretty beefy stuff here on a regular basis.
Steve Shumaker
USA 1183

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Re: My new boat

Post by joe.bersch » Thu Jan 05, 2012 3:20 am

Shu:

The failure we had was really quite minor and occurred after we put a massive load on the foil and gantry trying to bear off in a 25 knot stinger at the Gorge. It was in the first hour or so of Kris and I sailing together for the first time as we began training for the Worlds. This particular bear away, if caught on film, would not be used in a How To video. As luck would have it, we only got a couple more hours of sailing in the B6 before the first race of the Worlds, but that's another story. We made a small repair, were sailing the next morning, and put it to the test in Weymouth with no problems

In any event, the loads can be pretty substantial from lift, but I think they might be greatest when the whole thing is stalled and working more like a hand brake. I think this contributes to both foil and gantry failures. To exert maximum load on all components, wait for giant puff to hit at the weather mark (20 plus knots is suitable), feel rushed to bear off and therefore don't ease foil off to proper setting, heel boat to leeward, move aft in boat and bear off into the back of a wave. If you fight hard to keep the boat upright, determined not to let it go down the mine, you will adequately test your gantry/foil build.

In simple terms, I think failures occur in this system because it is easier for engineers to calculate theoretical loads from foil lift than it is to calculate the theoretical loads placed on the system resulting from the sheer determination of a skipper and crew to avoid pitching it in, particularly in front of an audience.

Joe

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Shu
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Re: My new boat

Post by Shu » Fri Jan 06, 2012 6:32 pm

Sounds like what Chris Johnson and I did in a massive gust in Hawaii in 2008. I Can still remember the feel of the tiller and rudder flexing as I heaved mightily on the tiller to force the boat around. The end result was a capsize to windward followed by the boat going down the mine all by itself.

I will need a boat that can survive such stubborness!
Steve Shumaker
USA 1183

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Re: My new boat

Post by Chris Johnson » Fri Jan 06, 2012 7:21 pm

I was thinking that it sounded like a pretty typical high wind bearaway for me! Except that most of the time, my determination to avoid pitching it in does not exceed the boat's determination to get rid of me...

Hendo
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Re: My new boat

Post by Hendo » Fri Jan 13, 2012 6:47 am

Steve , I sent you back(pm).
cheers
Kris

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Shu
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Re: My new boat

Post by Shu » Sun Jan 15, 2012 4:22 pm

After adding several layers of carbon cloth reinforcement on the bottom of the joint between the gantry and cassette, I turned the boat over and added two layers of 200 gm (5.8 oz) carbon cloth tabbing, oriented at 45/45, over all the epoxy fillets. I then added stiffeners to the top rails of the gantry. 1-1/4" x 1/2" foam glued to the outside of the gantry side plates, 300 gm (9 oz) uni strips on the inside and outside, then 200 gm (5.8 oz) cloth at 45/45 over the whole thing.
Attachments
I-14 875.jpg
Gluing the foam stiffeners in place. As usual, lots of clamps.
I-14 879.jpg
The bottom edge was rounded with a 1/2" roundover router bit prior to gluing in place. Note the fillets. The nails keep things from sliding around until the epoxy cures.
I-14 881.jpg
I rounded over the inside and outside top edges with a 3/8" router bit.
I-14 887.jpg
9 oz (300 gm) Uni strips on the inside and outside of the top rails. Peel ply still in place here.
I-14 891.jpg
5.8 oz (200 gm) cloth at 45/45 placed over the entire top rails.
Steve Shumaker
USA 1183

-TG
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Re: My new boat

Post by -TG » Sun Jan 15, 2012 11:47 pm

Like I said about 14 pages ago... You really need a clamp sponsor!!

Looks good Steve !
-TG
USA 1187
San Diego, CA

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