My new boat

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Shu
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Re: My new boat

Post by Shu » Mon Apr 30, 2012 6:03 pm

We kept hearing an un-nerving popping sound in the region of the mast on the last day of the Skiff Supercup as we tacked from one lazy pre-start reach to the other. Inspection once we got to shore showed that the torque on the mast was starting to crush the mast step's wood side pieces. The fully battened main, with vang off and sheet eased, can apply a lot of force to the upper spreader tips. I'll put the description of the repair with the original construction of the mast step in the August 28, 2011 post on page 19 of this thread.
Attachments
DSC_4658.JPG
Here with vang partway on and boom at centerline. Note the sail nearly touching the upper spreader tip. Imagine no vang and sheet eased.
I14-4-12 001.jpg
The sides of the mast step slot used to be parallel, not hourglass shaped.
Steve Shumaker
USA 1183

joe.bersch
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Re: My new boat

Post by joe.bersch » Tue May 01, 2012 6:53 pm

Steve:

That is interesting. The Killing 3 had a mast step failure at the Worlds in Weymouth, although I was under the impression it was a compression failure. You might want to check in with them to learn more.

The good news is that your new B6 Mast has no uppers! At least the torque will be gone!
I look forward to seeing your new rig in the boat.
Joe

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Shu
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Re: My new boat

Post by Shu » Wed May 02, 2012 10:50 pm

Fixed. Here's a photo showing the reinforced mast step. The inner sides of the slot have been reinforced with 1/8" pultruded (uni) carbon plate, and the side pieces drilled and filled with epoxy to strengthen the wood. Just some fairing and paint to finish the job, but it's ready to go sailing now.

Repairs tend to look very ugly until painted or covered with a neat layer of carbon; I think it's the mish-mash of wood, carbon, epoxy, old paint, etc. that does it.
Attachments
I14-4-12 016.jpg
Just some fairing and paint to finish the job
Steve Shumaker
USA 1183

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Shu
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Re: My new boat

Post by Shu » Sun Jul 15, 2012 3:34 am

I've been working on a couple projects: one to attach gudgeons to my Russel Brown rudder, and the other to replace my inadequate non-skid in the cockpit (dance floor).

For the rudder, I do not know the laminate schedule for the rudder head, so I've added a couple layers of carbon cloth to strengthen it. First, I vacuumed two layers of 200gm carbon cloth at 45/45 and 0/90 onto each side, overlapping the trailing edge to provide additional bond strength between the two sides. Then I vacuumed two strips over the leading edge at 45/45, overlapping onto the previous layers. For the gudgeon flanges, I'm using 6mm carbon plate.

For the non-skid, I'm using 3mm Seadek foam non-skid. The 3mm is now only available through special order, but 5mm seemed excessive. First I cut the foam to fit and traced the outline onto the grit-and paint nonskid. Then I sanded off the old nonskid (down to the carbon in many places). I then repainted the edges with Interlux's Perfection polyurethane to cover up the exposed carbon where it will be visible near the edge of the new nonskid foam. Installing the nonskid foam was fairly easy; I recommend watching the installation video on Seadek's website.
Attachments
200.JPG
Vacuuming two layers of carbon cloth onto the rudder head. Vacuuming in the summer sun decreases the cure time.
209.JPG
The reinforced rudder head, ready for attaching the gudgeon flanges.
213.JPG
The foil outline traced onto the carbon plate gudgeon flanges.
001.JPG
The old nonskid sanded off and the edges repainted. Ready for the nonskid foam.
007.JPG
The finished product.
Steve Shumaker
USA 1183

joe.bersch
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Re: My new boat

Post by joe.bersch » Tue Jul 17, 2012 3:44 am

Steve:

We put SeaDek on the racks and on the rail of my new B6. I think the SeaDek is an adequate product on the racks, but it did not wear well on the rail. It was hardly durable at all due to the open edges getting exposed to boot wear. I know that some like it on the floor, but in my opinion it doesn't provide adequate traction for me in a boat without kick bars. Perhaps it is my footwear too. I am a firm believer in 80 grit non skid tape. If only I could find myself a sailing gear sponsor as it is a bit hard on the equipment, for sure. I hope you find the SeaDek to have enough traction. If not, at least it is soft when you fall!

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Shu
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Re: My new boat

Post by Shu » Tue Jul 17, 2012 10:11 pm

Joe,
I've had good experiences sticking to the Seadek on Brad R's and Jake Skala's boats. I have two non-skid grits in the shop: one which produces a surface like a rasp, and the other which is gentle, but too slippery, and was what I just sanded off. I debated this with myself for a couple of months, talked with Kris about the grit he uses, but in the end decided to go with the foam. We had the boat out on Sunday (in shorts; I wouldn't try that with 80 grit) and it works great. I use the Gill booties, which have a really soft rubber, so maybe that makes a difference. I'll try to report back how it fares over time.

As for the Seadek on the gunwale, it's been on the boat since March and is already starting to get cut up. I wrapped it down onto the topsides and under the rail on the inside, so I don't have a problem with the open edges. I figure it's cheaper to replace than wetsuits and harnesses.

By the way, I'm enjoying your "old" B6 rig. I spend a lot less time looking at the main, because it always looks great. Just a quick glance tells me if I need more or less vang, more or less cunningham. No need to fiddle out the right combination of vang, cunno and caps to somehow will the main into a reasonable shape.
-Steve
Steve Shumaker
USA 1183

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Shu
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Re: My new boat

Post by Shu » Wed Jul 18, 2012 5:42 pm

This morning I cut out the foil shapes on the gudgeon flanges. I taped the two 1/4" carbon flange plates together and cut them together with a sabre saw. Cutting through 1/2" of carbon plate is brutal on saw blades. I used standard steel sabre saw blades, and they would only last an inch or two before the teeth became completely rounded. I then tried a very slow speed, about 3 or 4 cycles per second. This worked very well, and I was able to complete the cutting without ruining any more blades. My hypothesis is at slow speeds the teeth can really dig into the carbon and actually tear it out, rather than trying to slice it like a knife, which quickly dulls the steel. Some work with a rasp or dremel should get the cut-outs to fit over the rudder head.
Attachments
I14-7-12 005.jpg
Carbon gudgeon plates with the rudder head shape cut out.
I14-7-12 004.jpg
The carbon plate is brutal on steel saw blades. Slowing the reciprocating speed way down really helped.
Steve Shumaker
USA 1183

Chris Johnson
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Re: My new boat

Post by Chris Johnson » Wed Jul 18, 2012 8:52 pm

Steve - what you need is carbide grit blades. For example, McMaster Carr part number 4027A17. You can likely also find them at a good hardware store. They cut carbon very easily and last a long time.

Try a carbide or diamond grit bandsaw blade on carbon plate and you'll really be hooked...

The boat is looking great! I can't wait for Hawaii!

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Shu
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Re: My new boat

Post by Shu » Mon Jul 23, 2012 6:11 pm

I'll pick up some carbide grit blades next time I'm at the store. In the meantime here's more progress on the rudder. After consulting with Kris Henderson and Chris Johnson, I'm proceeding with a method that involves the parts I have on hand. The main issue is that a gudgeon hole through carbon plate will not wear very well. My original plan was to use G-10 bushings through the plates, but to get the clearance needed at the back side of the carbon cassette (some call it a "book") that holds the bronze pintle carrier, very little carbon plate will be left to take the rudder loads.

Kris H suggested using G-10 plates. If I did this I think I would start with 3/8" or maybe even 1/2" plate. Simple elegant solution.
Chris J suggested using the G-10 bushings through the plate, but also wrapping carbon tows around the bushings and onto the rudder .
I suggested using bronze bushings (thinner, therefore more carbon plate is available for strength)

In the end I went with the G-10 bushings with carbon tow reinforcement, since it uses the materials I already have on hand.
Attachments
I14-7-12 010.jpg
The G10 tube. 5/16" ID; 1/2" OD.
I14-7-12 015.jpg
Checking the clearance with the bronze pintle carrier and cassette.
I14-7-12 027.jpg
Spot gluing the flanges and G-10 bushing in place. Plywood spacers allow the flanges to be clamped in the precise alignment and spacing required. Note how little of the carbon plate is left to hold the bushing. Just a lot of very short carbon fibers - not strong enough.
I14-7-12 031.jpg
Here it is spot-glued in place. Once reinforced, the G-10 tube will be cut to fit.
Steve Shumaker
USA 1183

Hendo
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Re: My new boat

Post by Hendo » Tue Jul 24, 2012 5:18 am

052.JPG
Steve the back have of those goudgen plates are not doing much. As you notice with the Henderson boat rudder cassette ,
as you see it tapers in the aft section to reduce weight. The bottom is still wide to act as an end plate for the water , but very thin.

joe.bersch
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Re: My new boat

Post by joe.bersch » Tue Jul 24, 2012 1:35 pm

Steve:

I am curious why you chose this route rather than a rudder cassette like Bieker or Tuttle designed. After you are done with the gudgeons, what is your plan for a tiller?

RMK
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Re: My new boat

Post by RMK » Sat Jul 28, 2012 4:18 pm

I'm curious as to why the cassette still exists. Does anyone raise their rudder to launch or retrieve since the t-foil? Putting the rudder in from the bottom is a pain. I would think that the cassette is extra weight and a potential problem as far as slop in the rudder system. Simple is better.

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rand
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Re: My new boat

Post by rand » Sat Jul 28, 2012 4:31 pm

I think the main advantage of the cassette over the old way is distributing the load more evenly over the rudder head, which leads to far less failures (I don't remember the last time I saw a broken rudder). But I have to admit that pushing the rudder up into the cassette is a royal pain....
Rand Arnold
International 14 USA 1143
"A Bumblebee Called Kate"
(former US President, former US Measurer)

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Shu
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Re: My new boat

Post by Shu » Sat Jul 28, 2012 8:46 pm

Joe,
I will put a tube on top of the rudder and slide the tiller into that. When the tiller is in place it keeps the pintle from coming out when the boat is turtled.
Kris,
I'm not confident that the twisting force on the rudder head won't exceed the bond strength of the trailing edge; so the flanges provide some strength to hold it all together.

I'm with RMK and Rand. Lining up the gudgeons and dropping the pin in is so much easier than trying to slide the rudder into the cassette from the bottom. It should eliminate a little play that exists between a cassette and the rudder head. Saves a little weight too.

Here's some more progress photos.
Attachments
040.JPG
After pumping epoxy glue into the spaces between the rudder and the flanges, I've added generous epoxy fillets, and ramps from the G10 bushings to the rudder. The tows will run along the ramps.
054.JPG
Carbon tows over the upper gudgeon. The pintle is waxed and put in place to help keep the bushing in shape as the epoxy cures.
053.JPG
Carbon tows over the lower gudgeon. Not very visible are a few tows over the edge of the flange to help hold that thin bit around the G10 bushing together.
Steve Shumaker
USA 1183

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rand
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Re: My new boat

Post by rand » Sun Jul 29, 2012 5:20 am

I'm not sure that lining up the gudgeons and pintals is easy, I've bent a few pintal fittings when you're halfway there and the boat shifts or a wave or gust of wind... :oops:
Rand Arnold
International 14 USA 1143
"A Bumblebee Called Kate"
(former US President, former US Measurer)

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