dart 18 tangs
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Posted: Aug 18, 2014 - 04:16 PM
cats moored on mushroom anchors take lots of abuse from mother nature,have to replace tangs for bridals, completely decimated. looking for replacements in U.S. UK &Canada. diagrams show a second chainplate inside hull, that tang is screwed in to, I assume must place screwdriver or other object in each of 3 screw holes when screws removed, to hold inside plate in place; has anyone performed this task before? are inside the hull chainplates epoxied or fibreglassed to hull? all ideas and suggestions welcome. -
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Posted: Aug 18, 2014 - 06:41 PM
Can't help you with the parts, but I would modify my anchor rodes.
The wind pulls the anchored boat to the end of the line. If you use chain/rope, there is no give when a wave lifts the boat, the loads transfer directly from the end of the rode to all parts of the boat.
You have just discovered what happens when a small fittings are exposed to repetitious loading. It does not initially break the metal but creates what is known in engineering as "fatigue". Metal is much more susceptible than wood.
Cats are simply not designed to handle this. I would install a snubber in line with the chain/rode. It will need to be fairly long, so it will absorb much of the load, by stretching during load, then pull the boat back during the relax phase.
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Hobie 18 Magnum
Dart 15
Mystere 6.0XL Sold Was a handful solo
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Bombardier Invitation (Now officially DEAD)
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Posted: Aug 18, 2014 - 08:24 PM
Thanks for immediate reply. Have owned cats and beached them since 1969 only, until Feb in Florida, and now since July off long Island N.Y.& must confess my ignorance. Please describe snubber since you diagnosed the conditions accurately; we already lost mast and bridals on 5.7 nacra which resulted in torn tramp, broken tiller arms,etc,; forestay and mast on nacra 570. -
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Posted: Aug 19, 2014 - 09:12 AM
can't say we didn't warn you ... but don't worry, most of us learn the hard way too, even after being advised
On my cat they are epoxied in but i don't know about darts.
You could always change out 2/3 screws at a time but if the nuts on the backingplate aren't welded in .... you may need to cut open a small access to hold them in place
when i broke a side stay chainplate (all internal) it was near impossible to unscrew the screws. we used some type of impact screwdriver my friend had that you hit (HARD) with a small sledge hammer and it breaks free a frozen bolt (not exactly what i wanted to do to my cat)
IF you need to cut open an access area i recommend you create a small opening just big enough for your hand (AND FOREARM)and cut it open like the top of a pumpkin (at angles) so it will sit in the spot without falling in (so you can re-attach it later.. less work in the end)
I use 3.5' of chain and about 30' of 3-Strand Anchor Line. That stuff has a lot of stretch in it and is much better/softer on a boat than any type of low stretch line. ... but the more the wave and wind ... the more you need (as discussed in the other thread about mushroom anchor morning)
Edited by MN3 on Aug 19, 2014 - 09:15 AM. -
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Posted: Aug 19, 2014 - 09:32 AM
thanks, will install rope/line to anchor chain this weekend. info on line in U.K. is that Dart tangs are epoxied to hull, there is an inside chain plate, so far no luck on parts/tangs, Laser no longer supplies parts, Woody Hustler in Canada not responding thus far, emails to speedy sports and windsport in U.K. not productive thus far -
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Posted: Aug 19, 2014 - 09:49 AM
If your repairs are external , you don't need no stinking part...
go to any marine dealer and find a chainplate that is similar is size (needs to be exact where the holes are or go find/order blanks and cut your own holes ... there are many chainplates available online
bend as needed and screw in ....
that would be a very easy repair IF the nuts are welded to the backing plate
my friend had a dart 20 and he did that but i think he doubled up 2 chain plates and wrapped one around a custom front beam to support the over-sized (tornado) jib he flew
Edited by MN3 on Aug 19, 2014 - 09:50 AM. -
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Posted: Aug 19, 2014 - 10:39 AM
e mailed that 570 tangs ordered and will double up when i receive additional fittings as per your suggestions, thanks for your astute observations -
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Posted: Aug 20, 2014 - 10:40 AM
We used it on a 38' lead sled to dampen out the "chain yank". On that boat we had 50' of heavy chain, followed by 200' of rode. The chain itself acts as a damper.
Visualize your total rode, it is not a straight line, more like the letter "J" on its side. As the boat lifts in a wave it has to lift slack chain off the seafloor. The chain weight then wants to return to the seabed. This results in quite a bit of "give".
As MN3 mentioned, using stretchy line adds more give to the system.
The 3rd item is a snubber. On small boats it is bungee affixed to the rode in such a way that while at rest it creates slack in the rode. I don't have a photo, think of it as the letter "U", where "U" is the rode, & bungee connects the upper ends of each side of the "U".
The bungee has to be sized to the conditions. It needs to be strong enough to pull the rode back into the "U" shape between jerks, yet not so strong that it transfers all the shock load to the boat. I have seen monos using car tires as bungee.
The bad news is, it seems your boats are in an area of constant repeating loads. I honestly don't think any anchor will ever be able to eliminate damage to your Cats. They were never designed to be moored in a wave enviroment.
Looking at it from an engineering standpoint, all the wave loads get transferred to the boat, which moves, & transfers the energy back to the water. If you strengthen one item, it will simply continue to transfer the load throughout the boat, until the next weak link fails.
I would try to get permission to put in a lift that will raise the boat above the water. If it can be removed at season end, then it is not permanent, & may be classed the same as your anchor.
Good luck.
Edited by Edchris177 on Aug 20, 2014 - 10:40 AM.
--
Hobie 18 Magnum
Dart 15
Mystere 6.0XL Sold Was a handful solo
Nacra 5.7
Nacra 5.0
Bombardier Invitation (Now officially DEAD)
Various other Dock cluttering WaterCrap
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Posted: Aug 20, 2014 - 11:12 AM
thanks for reply and advice-wii try tire'bungee' idea, presenly have no other option but to leave cats at anchor. -
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Posted: Aug 21, 2014 - 09:26 AM
Be very careful when removing the tangs. On my Dart 20 one of the nuts on the inside of the hull fell off. There is a type of rivet that is threaded inside the shaft that Windsport U.K. recommended to remedy this problem. I found a U.S. supplier and used one to fix the problem. Another possibility is to install inspection ports to create internal access. By the way I have gotten many parts from Windsport without any problems. Let me know if you need more information.
Good luck,
Dan
Bradenton, Fl -
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Posted: Aug 21, 2014 - 04:05 PM
thanks for info- windsport problematic,utilizing Woody Hustler in Canada but 2 weeks for parts so we made up some as per suggestions on this site, installing fri -
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Posted: Aug 28, 2014 - 08:54 AM
Stainless tangs fashioned by joe pogostin ugly but work only: one screw held on port bow so pop rivited tang( photos after labor day since we have all 3 cats sailing nacras 570&5.7 & dart 18.) Finally saw other Stu FROM fAIR HARBOR Uowever, out with his wife(some still sail after they hijack their mate) on supercat with new Milar sails, which kept up with 570.
