Rolling Hitch on Snubber

[estarzinger]

Originally Posted by JonJo

The other downside to climbing rope is the inability to splice, though maybe Evans has or is looking at that.

I mentioned this somewhere else but . . . . link: NER heavy duty kermantle eye splice

I note Evans measure of yacht speed, as less than 2 knots, which starts to put a figure on the energy developed but I think Evens was measuring yawing - anyone with ideas of movement through wave action, pitching, hobbyhorsing?

The data I had was from cm accuracy gps, and the boat speed was 'near instantaneous' (using Doppler data from one time slice and not speed between two measurements). It was suppose to be accurate to .05kts (in any x/y direction, a bit less accurate in the z direction.) I don't have the unit anymore, was just loaned it (because I superyacht I was project managing was interested in one). My sense is that for a snubber, with decent (say +5:1) scope out the x/y velocity is the relevant part and z velocity is not so important. I never saw more than .3 kts of x/y velocity while anchored. However, this would probably depend on the vessel. I would except to see higher velocities with your cat.

.............

[JonJo]

Evans,

I have seen another link to splicing kermantle as well as yours but I have not had time since to open up kermantle as in dynamic climbing rope to see what its like under the braid. My splicing of braid is not well practised, it takes me 2-3 hours to do each eye splice - maybe I should do more!

Its on the 'to do' list!

Thanks,

Jonathan

[SailFastTri]

Originally Posted by Cotemar

I agree with you that my 5/8 three strand nylon snubber is too big for my boat. Instead of going with smaller line I will try these rubber snubbers this year which will give my 3 feet (1 meter) of stretch per bridal leg. The reason I do not go down a size from 5/8 line is because a broken snubber on my cat would allow the tightened chain to hit my hulls at the worst time in storm conditions.

I know some of you guys do not think these rubber snubbers are any good, but a few cruisers at my marina have been using them for 10 years without a failure, so time will tell if it will work on my boat.

The stainless shackle attaching your snubber to the cross-beam fitting appears to be the weak link. Not only the material, but the angle of pull on the shackle.

http://cdn.cruisersforum.com/forums/...3&d=1369918580

[s/v Jedi]

Originally Posted by SailFastTri

The stainless shackle attaching your snubber to the cross-beam fitting appears to be the weak link. Not only the material, but the angle of pull on the shackle.

http://cdn.cruisersforum.com/forums/...3&d=1369918580

I find the whole picture disturbing. Eyesplicing the snubber and replace stainless shackle with a soft shackle would be my #1 priority on this boat.

[estarzinger]

Originally Posted by Fuss

Sorry to be a bit out of step, but what size are these 5mm,6mm or 8mm dyneema?
Thanks John

I am using 8mm, which appears to be the biggest that will easily fit thru 10mm chain links after its been 'doubled' in the soft shackle construction.

[JonJo]

Cotemar,

As it seems you are to do a big re-fit of your snubbers maybe think of this one. Keep your short bridle snubbers, but thin them down. Fit another snubber from the centre of the cross beam but make it work, but slightly less work, when the other 2 are at maximum stretch (the 3 snubbers can now be all joined together). If a side one fails the load should then be shared by the centre one and the good side one left.

Centred 'bow' rollers under the mast are a great idea, keeping the weight central but are a nightmare, if as you suggest a snubber fails, and a regular nighmare if you need to take the anchor up in strong winds - the pivot point under the mast allows the yacht to buck all over the place. There does not seem to be a solution, other than adding a bow roller under the cross beam (which I have seen done on bigger FPs) or have a look at a Catana, the new 42 has an underslung bow roller at the cross beam if you have any nearby.

Jonathan

[Cotemar]

I will try this bridal for a bit to see how it behaves.
It seems to be working very well so far and there is no snatch loading.

[Kettlewell]

That bridle looks good to me for anchoring 90% of the time, but it appears the lead where the shackles are attached at the end of the cross beam will put a side load on the shackles, which could be an issue in bad conditions. Maybe it's the photo, but those shackles look pretty small too--I would think they should be at least close to the same size as your anchor shackle, or maybe one size down would be OK. But, there is a potential that one leg of the bridle could end up taking the full anchoring load if the other leg should go for some reason.

[Cotemar]

They are 3/8 shackles up from 5/16 on the anchor .
All the knots are figure 8 and I just have to cut of the excess when I have a free moment. The brown color is grease not rust.

[Kettlewell]

I worry a bit about the sideways pull on the shackles. Of course, that problem would only show up with lots of wind and strain. You might want try just a lashing around the ends of the cross beam, possibly through the middle of the base of the cleats to hold the lines from sliding towards the middle. If it appears chafe is an issue you could use Dyneema or encase the line in chafe guard. Also, I suspect those shackles will rattle a bit in the right wind conditions.

[s/v Jedi]

The solution to the sideways pull on the shackle is to replace them with softshackles:

Also: Instead of all the hitches and/or shortening the rope, simply put eye splices in and consider using the extra length instead of discarding it.

[JonJo]

Another way is to put a big tang, designed at the correct angle, on the cross beam bolt. Ours has a tang welded to the securement plates to which the cross beam is attached at the correct angle - but we are not using them now and have had turning blocks soft shackled to the bow cleats which we have been using for some a year or so now. We are about to fit padeyes on the bow so we can use them as dedicated attachment points.

I looked at a new Catana 42 10 days ago - they had no bridle attachment points at all - I (and the dealer) assumed the bridles would need to be attached to the bow cleats.

The nylon snubbers themselves seem a bit beefy for a 6t Mahe, or more than 12mm (which would be more than adequate), especially as the load is taken by both equally But maybe the image gives the wrong impression of size.

Jonathan

[Kettlewell]

Cotemar may get a chance to test things out tonight and tomorrow as Andrea tracks right up the coast, but it only looks like gusts in the 40-50 range at the worst. Sometimes though these little storms cause a lot of damage because they move so fast and people get caught unaware and make no preparations. I have had to secure other people's boats around me during storms like this in order to prevent them from breaking loose and possibility hitting my boat. The good news is the mooring painters and bridles are probably mostly new line for the new season in New England.

[Cotemar]

It will get interesting around here tonight when Andrea blows through. I may have to worry more about the 4 inches of rain than the wind and waves.

[Kettlewell]

Good luck. If I am not mistaken the remains of Andrea should pass south of LI meaning you will have strong winds from the SE, then E, then NE, then NW--backing winds. Hope you are protected from that direction.