paxfish
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Posts posted by paxfish
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I agree, but it turns out he had some high tech tapered carbon battens in at the time. They will be replaced with something more appropriate in an attempt to get that draft back to 40% or so.
I'll have to make that judgement when I actually get to haul the sail up the mast.
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So - to zero in on the boom even more, when I watch a boat like Charleston in the video below, it appears the boat has no outhaul at all. Foot tension is achieved primarily by cranking in the mainsheet because of the angle of the boom going to the crossbeam rather than the mast. Do I have that about right?
If so, I LIKE IT!
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That's a good question - I will see what I can find out. I know the mast is the one actually shown in the picture above and is all carbon.
I just learned that the sail in question was cut too short in the foot by UK, and the customer demanded a new sail. (new one shown in picture above). That is why this "new" one is available.
The good thing is that the owner is willing to let me fit the sail on the boat before committing to buy...
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Hoo man - This thing might come to fruition. Closer measurement reveals that I might be able to use it without cutting, just a bit more area down low. Boom is the right length and I could lower my gooseneck. This is a big purchase for us - all comments welcome.
The sail was built for a highly modified F31R that blew up and hence the sail was never used after the initial fitting.
The sail looks like this:
And here is what it looks like overlayed on my sail plan. It would move my CE forward a bit, which would be just fine frankly. I still have significant weather helm when sailing close to the wind.
It is located 1200km from me, and the battens make for an expensive freight shipment. Still mulling it over.
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Thanks Bad Kitty.
Hi Scotti - Yeah - in the winter, I'd roll it up in the cabin. But for 6 to 7 months, during the season, it would spend a lot of time flaked on the boom under a sunbrella cover....
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Guys - Through a friend, I've stumbled into an opportunity to buy a new UK Carbon Load Path Main built for a tri for 1/5 of it's original price. The guy had the sail made four years ago, and it has been sitting ever since. Will a sail like this hold up to being flaked on my boom under a cover for 6 months out of the year?
Seems like a heck of a deal at $2000 USD. The Luff is about a meter too long, but the first reef point should tack in just about right. I should be able to cut off the bottom panel and go with it...
Your thoughts?
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Good thinking, and I will watch it closely. There will be a furling drum right above the hook, and I'm betting that will keep a gybing sail away. But you're right, anything can happen in the heat of battle!
Also - the hook is immediately above the tack for a spinnk/gennaker, and there is typically several layers of strong cloth at the tack. Fortunately, the hook is ground pretty smooth and should not catch cloth. The bend of the hook will be somewhat crowded anyway, with furling gear and a line to the seagull striker.
Here is what it will look like properly rigged up:
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I am having a bushing machined out of G-10 as well. This will be inserted into a hole bored in my stems.
Looks like this:
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We are in the depths of winter here. Had a blizzard 10 days ago resulting in a meter of snow and 50 knot winds. Most of it has melted. Fortunately, my wife and I were in CostaRica!
Despite that, I've made some progress on Terrapin while she's in the yard. A friend of a friend built me a nice sprit. He machines the ends and has them anodized. It has a hole on the end for a spinnaker tack which runs inside the sprit and out that slotted fitting on the other end. The hook is for a furling screacher. The socket has a nice delrin insert and the socket "collar" is nicely machined to fit the profile of my forward crossmember.
Next up is to drill the holes for the bobstays. The stem is about 100 mm wide, and should make a nice mounting point.
Here's a couple of shots:
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Damned Shame - Looks like she was well found.
Tennant design?
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I was thumbing through some old Multihull mags - Anybody know the history of this battlewagon from 1998?
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The boat looks great, Madyottie!
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The red ball is on the unloaded side of the dagger board case -- where the board isn't even touching the case.
/Martin
Gotcha - Of course!
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Very cool. Intuitively, I would expect to see some red arrows near the ball.
i wish I had taken a couple of photos while laying glass. But I was busy!
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So, I'm a do-er. Armed with Martin's excellent analysis and a warm day, I forged ahead.
I removed the floor in that area, and any damaged glass. On the inside, I layered uni, DB and Triax where it seemed appropriate (certainly Martin's presentation was in my head), I also wrapped 150 strands of heavy uni between the back of the case and the hull, wrapping them around fore and aft, and then let the strands splay like outstreched fingers in several directions. This will further support the board on the opposite tack (though there was no apparent problem there.
Another layer of glass, replaced the floor, a couple of layers over top. There is no horizontal beam in addition to the floor as yet. It doesn't "feel" like it is necessary (sole is sufficient now, with the heavy glass extending from there to the dagger board exit 2cm above it.) I added about 5 pounds of material overall, but removed about half that previously while grinding. I removed 31 pounds elsewhere and my net will be negative!
Once everything cured, I ground out any remaining bad glass on the outside, and will soon re-glass there to clean everything up. (need a warm day!)
Meantime, back at the house, I'm starting to tackle the dagger repair. Eventually, I will build a mold and make new ones, but for now, I am repairing it.
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Fascinating! I like your style, Brother!
The last slide is the most telling for me. Without the floor, the left image shows a tremendous amount of stress on the hull bottom adjacent.
The right image tells a lot too: It "feels" like a significant wrap of "Gunstock" (Tennant's term for Uni) running between the hull and the dagger case and then back around and splayed out along the hull/floor would go a long way toward spreading that stress. Are my non-technical instincts correct?
To take that further, it seems like the forces at the leading edge and trailing edge are huge. The board seems to be trying to tear the boat apart in that area. And in fact I did have a lengthwise crack both fore and aft in those areas. The core was not wet, at least not yet. I DO plan to put further reinforcement in that area.
Those cracks are in evidence here:
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Interesting. I see your point about having a longer daggerboard to potentially take advantage of a higher shelf.
Wildfire's shelf is 500mm above the hull exit.
I'm thinking some extraordinary event occurred to cause both the dagger to break AND the inner edge of the hull exit to crush. A hard sideways impact of some sort.
I removed the floor in that area and layered up the inner side of the hull over the weekend. it won;t crush again, at least not in THAT area! I expect to start grinding on the outside over the next week. The weather is down to 0 C this morning. I'm sure that will slow progress for a while....
BTW, whether it was an intentional or accidental typo, "finite elephants" is funny either way....
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Very cool. Lotsa pics of the rehabilitation are requested!
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No sole in my boat. None specified and my boat is small with some 1.3 m head room so adding a sole would not really add to comfort.
I see Tennant stuck to the same design we rejected back in 1985. There were a number of things we change in the structural engineering. The only things that have broken are things we did not change such as the cross beams.
Yes, the sole helps distribute the load but only from one side unless you wrap fibres around the dagger board case and spread them onto the sole.
Are you in a hurry? If not, why not spend some time on a bit of proper engineering before slapping on more material?
/Martin
Not in a hurry - I'm out of the water for at least 4 months for winter I certainly appreciate your Tennant experience and insights. Winter will limit my glassing days though as the boat is outside. So there is some sense of urgency.
The sole isn't much - 6mm exterior ply. I have some 18mm carbon core (similar to Coosa) with which I might replace the ply. Laying in uni to tie in the sole sounds like a good approach as well.
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Nice carpet.
Wise Guy! Yeah, being a finish carpenter by trade, the builder did a few things very nicely. That "carpet" is that mouse fur stuff - very light, but more inviting for guests I suppose. Terrapin is a daysailor first and (hopefully) a racer second.
Here is a shot facing aft from the head in the starboard hull:
He put that green KIWI grip on the floor. I had to sand it off on the other side, and wow that stuff is tough!
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Thanks Guys. Below is the drawing showing the shelf etc, and it is built to plan. The shelf is 12mm ply and supports the upper part of the board. It has many strands of uni "gunstock" rope around it as well to tie it into the shelf and the side of the hull. That part seems intact.
My intention now is to remove the sole roughly 3cm around the opening, grind out any fractured glass from the cracking and lay in many layers of triax and db. No core is compromised in this area as it is all glass. I will then replace the floor and let it make a horizontal column to further distribute the sideways load of the board.
The back side (inner side of the case) appears to be well bonded to the hull at this time, so no changes there.
Then I will also attack it in similar fashion from the outside, removing any fractured glass I find and rebuilding. Glass and more resin are on order!
Thanks all for your input. Martin - that is beautiful work on that trunk. I'm surprised you have no sole in that area (or was it added later?) I think the sole would be critical in distributing point loads from the dagger case....
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But first, I must repair the crushing around the dagger well. I intend to lay 4 layers of glass on the sole, and then carbon core foam horizontally across the sole to tie into the opposite hull. Then overlay four layers of cloth to make a horizontal column (and tripping hazard!).
Got any better ideas? Clearly there is a ton of force in this area, and I think there a design or build issue in not having it supported from the back side. this may have been in the interest of achieving headroom in the cabin....
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Can't seem to keep foils on my boat.
I've got a long thread on boatdesign.net on this one, so no need to hash it out here I suppose. I am exploring having new daggers CNC'd....
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Enjoyed it. One of those things you think you understand, but that rig really illustrates it well!
Flaking a Load Path sail on the boom....
in MarineTalk
Posted
I just received a better picture of the sail. It was used for one race, and the owner demanded a new one since the foot was 6 inches out of spec (too short).
It is being shipped this week, and I should be able to haul it up the mast soon to get a rough idea on fitment. I know the luff is too long. It is entirely possible the first reef might be just right. Or I might be lowering my gooseneck. We shall see.
#24 in the center. It is mounted on a highly modified F31 that was significantly lighter than stock. I think the main hull was bumped out 2 feet as well.