Dyneema or Wire Rope Davit Falls?

[estarzinger]

Originally Posted by conachair

One small point is terminating onto the winch drum, any force with no wraps can slowly undo a stopper knot though that shouldn't affect your application.

Just fyi . . . there is one (and only one as far as I am aware/tested) special purpose stopper which will not slip in dyneema - EStar Stopper | How to tie an EStar Stopper Knot | Knots

[Dockhead]

Originally Posted by estarzinger

Just fyi . . . there is one (and only one as far as I am aware/tested) special purpose stopper which will not slip in dyneema - EStar Stopper | How to tie an EStar Stopper Knot | Knots

That's a hot tip.

What I did was this --

The old Simpson davits have a screw and nylon bushing, to hold the bitter end of the davit fall. The old wire rope falls had eyes spliced in the end for this.

I simply spliced an eye into the bitter ends of the new dyneema falls and attached them the same way as the original ones.

I also used enough dyneema rope that there are a number of turns on the drum, even when the falls are fully extended. I believe the loop and screw is for last ditch security in case the fall is wound right out to the end, but ordinarily, the friction from the turns on the drum will be what holds them.

[estarzinger]

^^ That is nice - splice is a preferred approach. Some systems have a clamp, which is ok if well designed. And the stopper will work if that is the only option. The stopper does not slip but does reduce strength, however strength is usually not a huge issue with this application.

[Dockhead]

Originally Posted by Neziak

Did you change the wire to dyneema in the end? If so, can you share your experience and what modifications you ended up making. I have a pair of Simpson S225 manual davits and thinking of doing the same.

Yes, I did!

I didn't modify anything. Just made up two new dyneema falls, rather longer, and the same diameter (5mm) as the old wire ones. Eyes spliced in both ends. Put a shackle through the eye on the working end and used it just like the old one. Unlike Poiu, I kept the old weights.

It seems to work just fine. Interestingly enough, I did not use the davits at all (!) during the summer -- I deflated and stowed the dinghy on the foredeck after every single use (it is that easy).

But now that I'm back in the UK in home port, the dinghy is now hanging in them. The dyneema falls seem to be just fine, and they don't touch anything which could chafe them except two nylon rollers at the ends of the davits.

This seems to be a modification with no downside.

I hated the old wire ones, which kinked and tangled and slashed my hands with meat hooks. So I'm very pleased so far.

Edit: Another plus is that the much more flexible dyneema rope makes the action of the davits much smoother and nicer.

[Neziak]

Thanks Dockhead. I will do the same.

[dwf]

Hello,

Having problems with our Simpson Davits series 7 model S225 manual, I was offered by Cooney to replace them against 8000€.

The structure of the Davits is fine it is the mechanism that needs a refit.

Since there is no available parts apparently I was very interested in your repairs.

Do you have pictures or an exploded view of your Davits?

I understood you had the missing parts made in Manchester could you tell me the shop ?

I was thinking of electrifying and going to Dyneema like the new series 10, is this what you did on your boat.

Your advice and suggestions would help us a lot.

Thank you.

Denis

Originally Posted by poiu

I did just that 5 years ago for the same reason and more, I got a spiral wrap and tangle in the davits with the wire, it took half a day to fix and unbend the kinks. Horrid stuff. It was a straightforward change to dyneema. A big success. Grab it without fear.

I bought the higher tensile strength (Marlow Dyneema Max) option dyneema rope in the same diameter as the steel wire to give headroom due to UV strength losses and chafe. I also bought a few foot longer than the old wire thinking I would have to regularly redo the end splice because of chafe, but I haven't really needed to shorten it yet. There is a little chafe from the pulley and it probably will be best to shorten it now. The middle section is like new.

There will be some creep going on and now I probably should re-splice the end 4 feet from the drum plus a bit to be safe. That will fix the chafe issue at the same time.

One of the biggest problems I had was in the rope (and wire) jumping off the sheaves and jamming tight down the sides. A frequent and very frustrating repair. I had machined stainless sheaves, much wider to fill in the gap and to have a much deeper groove. The rope never pulls out nor jams now, a huge improvement.

I welded the head of a socket bolt to the centre of the crank handle and now can use an electric drill to power them. With my heavy 230kg dinghy it is a big help. For yours, maybe less so.

I also rebuilt the internal gearbox with new tougher high end stainless gears and sealed ball bearings. I had a big wear problem. That reduced wear, friction and improved solidity.

[poiu]

Originally Posted by dwf

Hello,

Having problems with our Simpson Davits series 7 model S225 manual, I was offered by Cooney to replace them against 8000€.

The structure of the Davits is fine it is the mechanism that needs a refit.

Since there is no available parts apparently I was very interested in your repairs.

Do you have pictures or an exploded view of your Davits?

I understood you had the missing parts made in Manchester could you tell me the shop ?

I was thinking of electrifying and going to Dyneema like the new series 10, is this what you did on your boat.

Your advice and suggestions would help us a lot.

Thank you.

Denis

I made some of the parts myself. The gears were made in a gear shop and they said the job was so hard they will not make them again. This was due to my choice in alloy, but any gear maker will make that part.



If you want, send me pictures and drawings of what you have and I will see if my drawings will work. Then I will modify or say if they are suitable to use. You will have to find local machine shops to cut the parts for you.

[Dockhead]

Originally Posted by dwf

Hello,

Having problems with our Simpson Davits series 7 model S225 manual, I was offered by Cooney to replace them against 8000€.

The structure of the Davits is fine it is the mechanism that needs a refit.

Since there is no available parts apparently I was very interested in your repairs.

Do you have pictures or an exploded view of your Davits?

I understood you had the missing parts made in Manchester could you tell me the shop ?

I was thinking of electrifying and going to Dyneema like the new series 10, is this what you did on your boat.

Your advice and suggestions would help us a lot.

Thank you.

Denis

My advice is that the Dyneema davit falls are excellent. I would never go back to wire rope. I am completely satisfied. No more meathooks, pleasant to the touch, quiet, and so far completely reliable. The conversion was easy -- just buy some single braid Dyneema, splice loops in both ends, and Bob's your uncle.



I would advise NOT to electrify your davits, though. The electric mechanism is Rube Goldberg and horrible. Be happy you have cranks.


I replaced my electric S225's with some older, smaller ones (S175's with cranks), and still have the S225's. I would be glad to sell you the mechanisms out of them, or the complete davits, if you want spares.

[dwf]

Thank you very much for your kind and quick reply.
My problem is that the socket for the handle seems of centered and that puts a lot of friction. I have pictures but can't get them through the forum.

My private mail is deniswfoster@gmail.com I could send you the pictures to make things clearer.

[dwf]

Thank you for your reply and advice.
I am convinced Dyneema has great advantages. I thought you had to do important modifications on the mechanism for it to work correctly. (dixit Cooney).
How much would you sell the electric mechanism of your S225 for and the whole davits for ?
Where are they located ?
Best regards.


Denis

[Dockhead]

Originally Posted by dwf

Thank you for your reply and advice.
I am convinced Dyneema has great advantages. I thought you had to do important modifications on the mechanism for it to work correctly. (dixit Cooney).
How much would you sell the electric mechanism of your S225 for and the whole davits for ?
Where are they located ?
Best regards.


Denis

My davits are in Cowes. If you're interested, PM me and we can continue offline.


Interesting that Cooney say modifications are needed -- did they say which ones? The only thing I had to think about was the fixing to the winch drum -- I used a plastic washer to protect the dyneema from chafe, although that was probably not necessary since that bit is not really under any tension if the fall is long enough (and I made it longer).


It runs fine over the plastic sheaves at the end of the davit and winds up fine on the drum.




Incidentally, I got the same song and dance from Cooney about replacing my davits with a new pair for £8000 or whatever.


Does it not occur to them, that if they refuse to support their own products only 10 years after they were last made, that someone might hesitate making such a large investment, just to face the prospect of hearing the same thing in another 10 years?



Really expensive gear like that, ought to be supported in a manner commensurate with a useful life which makes sense considering the cost. No one I know is willing to just toss out and replace something like that costing £8000, as if it were an obsolete I-Pad.

[dwf]

Here is a picture but I am not sure it will be visible on the forum.

file:///var/folders/8q/zbh7k8qx53vf5kkgbtdrhd_w0000gn/T/IMG_2616.jpg

Thank's again

Denis

Originally Posted by poiu

I made some of the parts myself. The gears were made in a gear shop and they said the job was so hard they will not make them again. This was due to my choice in alloy, but any gear maker will make that part.



If you want, send me pictures and drawings of what you have and I will see if my drawings will work. Then I will modify or say if they are suitable to use. You will have to find local machine shops to cut the parts for you.

[AtlanticX]

Dockhead, your post from several years ago was very helpful as we just took possession of our boat and had to replace the wire cable hoist from one of our Series 8 225kg Davits. Fortunately, the previous owner had a spare cable on board. I was talking to Cooney marine and they are trying to sell me on a significant upgrade to switch to Dyneema which seems unnecessary.

Could you share any images or description of the splice you made to connect the Dyneema line to the drum?

Thanks!

[Dockhead]

Originally Posted by AtlanticX

Dockhead, your post from several years ago was very helpful as we just took possession of our boat and had to replace the wire cable hoist from one of our Series 8 225kg Davits. Fortunately, the previous owner had a spare cable on board. I was talking to Cooney marine and they are trying to sell me on a significant upgrade to switch to Dyneema which seems unnecessary.

Could you share any images or description of the splice you made to connect the Dyneema line to the drum?

Thanks!

This is an old thread -- I've now been living with the Dyneema davit falls for more than 3 years, and I can report that I am delighted with them.

No more meat hooks, no more broken strands, kinking, etc. The Dyneema is much easier and much nicer to handle, is much easier to install, and is just generally better except for chafe resistance, but there isn't really anything to chafe against, so my 3 year old davit falls are still like new. I bought enough of that size Dyneema to replace them a couple of times but I don't see replacement on the horizon so I have started using it for other purposes.

I simply did eye splices at both ends of the falls, and use the same screw and washer to secure to the drum as the wire ones were attached with. Works great.

The splice I used is just a standard single braid eye splice using interlocking Brummel eyes and a long tapered bury. Easy and quick to do.

Why this would be a costly upgrade from Cooney I have no idea. Just buy some Dyneema and do it yourself -- quick and cheap.


One piece of advice -- make the falls about twice as long as would reach to the water -- so that you always have abundant turns around the drum. Single braid dyneema is slippery and I wouldn't want to rely on just the screw.

[AtlanticX]

Thanks for the very quick reply (especially given the age of this thread)! That all makes sense and I'm going to be making the switch to Dyneema for sure. I was shocked when the previous owner told me that he would replace the metal wires on the Davits almost every year and then was horrified when my first weekend with the boat I ended up having one break on me and then encountered all the meat hook issues, etc. Good tips, much appreciated!