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PostPosted: Feb 9th, '18, 10:01 
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I have been investigating the possibility of replacing the stainless steel cable with Dyneema/Spectra. There are quite a number of posts from members who have done something similar on their boats and most reports are positive.

Some of these have been for Ultimate swing keels. However when looking into this for the Ultimate drop keel a number of issues complicate things.

The current system has a manual wormdrive winch inside the transom with a single 5.1 mm SS cable feeding down to the underfloor via a block shackled to the inside lower pintle mount. A second block under the middle of the floor feeds the cable low enough to align with a small open slot in the cabin sole that leads onto a small sheave at the bottom of the aft keel support feeding up towards the top of the support. From there it leads to a small plate that connects to a pair of smaller 4.2 mm cables that lead up to the top of the rear keel support where there are a pair of wire sheaves. One leads down to the top of the rear of the actual keel and the other leads across to the final sheave on the top of the forward keel support and down to the top of the forward end of the keel.

Attachment:
UltimateDropKeel.jpg
UltimateDropKeel.jpg [ 45.63 KiB | Viewed 334 times ]


Have any other Ultimate drop keel owners tried replacing SS with Dyneema and can they share their experience?
Are there any Ultimate drop keel owners who have had wire faliures and if so, what was the mode of failure?

It is not straightforward to simply swap out the stainless. The issues are;

1. Attachment to the winch drum. Currently this is via a 3/8" round head bolt through the cable swage. I think this causes issues with the stainless whenever the cable runs over it and I suspect that this is what causes the visible damage I can see on the current cable. I also think that using a similar method for Dyneema would be even more problematic.

2. The two underfloor blocks are often running in bilge water. Will dirt and water ingress into Dyneema reduce strength?

3. The pair of sheaves on the top of the aft keel support only have 22 mm width to fit in. ie about 10 mm each. It will be difficult to source (I think) replacement sheaves appropriate for rope.

A really close inspection of the SS cable reveals that:
a . For the 5.1 mm cable: the section that winds onto the winch drum has the most damage, the centre section has no visible damage, and the last section that feeds under and up the keel support has some damage.
b. The pair of 4.2 mm cables have no visible damage.

My plan is to replace only the 5.1 mm cable and leave the pair of 4.2 mm cables in place. As they split the load they are less stressed than the thicker cable (greater combined cross section) and I can then leave the pair of sheaves in place.
I will try to work out some other method of securing the rope end to the winch instead of using the 3/8" screw. Perhaps some form of hitch? Or drill an angled hole through the drum cheek?

Anyway......I would really appreciate any opinions about the above.

Many thanks, Kim

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PostPosted: Feb 9th, '18, 14:10 
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No - I am not experienced in this and have never done it but read something about it for a F6k on the internet - see viewtopic.php?f=55&t=13895&p=163840&

This link suggests a brummel splice as a means of attachment. If you keep a handful or so of turns on the drum at maximum extension there should be little load on the drum attachment anyway. Dyneema is slippery with knots but perhaps an arbor knot *might* work as an alternative - used to attach fishing line to reels http://www.animatedknots.com/arbor/ - not recommending this, just suggesting. Need to do some testing to ensure it doesn't slip.

Do a google search, dyneema is hydrophobic / water resistant / unaffected by water.

Do you really need to replace the sheaves ? They may surprise you with the diameter that they can take. There are loads of posts here about people changing halyards from wire to dyneema. A lot seem to have gotten away with using existing sheaves, just check for any burring first.


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PostPosted: Feb 9th, '18, 14:19 
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Stainless does not like at all being wound onto a drum. It will fray quite quickly - better to use Gal wire I think. Before I swapped out the stainless to dyeema on my keel winch, only the stainless cable on the drum was showing signs of stress and this aft only 12 months and not a real lot of use either.

Replace the lot with dyeema. I have down this on the castle 650 keel winch. My drum has a side break out for the cable with a clamp screw. I use the same for the dyeema but double over the dyeema then clamp it and then start the dyeema with a few half hitches on the drum. i.e. the bitter end on the drum does not need a complicate knot - as long as there are multiple turns of dyeema covering it it will be fine - the dyeema will flatten down a lot so the extra turns will not impact the drum capacity. I do the same for the boat trailer winch. There are means to tie dyeema off if you want to reduce the amount on the drum - check out 4 wheel drives sites.

Edit: one important thing to remember. Dyeema is flexible, stainless is not. Thus GUIDANCE of the dyeema may be the most important thing to watch out for. Where stainless will self guide to some extent over pulleys dyeema will not . . . I had a case where my keel winch (with dyeema fitted) was wound the wrong way, then the correct way. The wrong way winding got the dyeema all tangled up in the winch. This will NOT happen with stainless or gal wire. So as long as the dyeema is under tension all good, if it can be slacked off . . . be careful . .

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For this message the author bachus has received thanks: Tezza (Feb 9th, '18, 14:29)
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PostPosted: Feb 9th, '18, 16:02 
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Fear not , i replaced my b20 tackle first with spectra then with ridiculously thin dyneema with no dramas at all .. build in a bit of over spec'ing and you will save weight and have a much friendlier tackle to deal with when replacing in the future :D


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PostPosted: Feb 9th, '18, 16:37 
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Thanks everyone for so many replies so quickly. My biggest issue looks like it may be the attachment onto the drum. Check out this photo. I took the drum off to better consider my options and now I can see why the SS cable gets so damaged and why there is so much clunking as the turns slip over or past the head of the 3/8" screw. Ouch! No way I will put it back like this.

Attachment:
WinchDrum.jpg
WinchDrum.jpg [ 79.17 KiB | Viewed 272 times ]


As you can see there is not a heap of capacity. Unfortunately there is only a mm or two clearance between the winch body on one side and the gear (epoxied and bolted on) on the other. So drilling a side hole may not be possible. Perhaps I will first make an eye in the line, and then after passing it over the drum and back through the eye so it cannot drop off, then try the arbor knot as suggested by Dave or put on a number of half hitches.

Most of the 4x4 sites that discuss winch line attachment have winches with side holes or some other arrangement. I'll do some more digging.

Good point Bachus. Particularly with regard to the two blocks under the cockpit floor. I can picture them flopping down onto their sides when the tension is released and possibly leading to a jam. I may have to see if I can fit some 'stand up' springs.

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PostPosted: Feb 9th, '18, 18:06 
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Here is a possible approach.

Make a hollow plug that will sit within the existing 3/8" threaded hole.
Feed the line through and tie a stopper knot.
Insert into hole and ensure that there is at least one layer of wrap over it to hold it down and in place.

I'll get some cheep polyester line tomorrow and fool around to see if this idea has 'legs'.

Attachment:
Drum2.JPG
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PostPosted: Feb 9th, '18, 18:22 
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Is there enough material in the base diameter of the drum to drill an offset holethat goes in one side, misses the shaft and exits the other side.

If you can drill one or two holes through the drum, that may give you the ability to anchor the line without creating too much interference with the tight line.

The entries and exits from the holes would need to be relieved with something like a dremel to avoid tight turns on the line. One installed, the anchored line could be covered with epoxy to reduce bumps that might compromise the tight line.

Consider clamping the tail of the line with pop rivets, big pop rivets. Not sure how I would do this.

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PostPosted: Feb 9th, '18, 21:36 
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My immediate reaction is to replace the wire with Spectra. The cable for my swing keel follows a different route to yours, and less of it is exposed to water, but it shares many of the features of your system. I use Spectra, and would NOT go back to wire.

Problems with wire (gal or SS) - does not like being wound round drums and sheaves, vulnerable to corrosion (will break at the most inconvenient time), frayed wires will damage something before the whole thing breaks, too much elastic energy when tensioned (can do some serious damage when it breaks)

Benefits of Spectra - no problem with being wound round drums and sheaves, OK about getting wet, fraying will not damage housings and sheaves, won't hurt as much if it ever lets go (it won't take your head off, like wire).

The only things you need to watch for are guidance on the sheaves, as already noted (not difficult with the right sheaves), and stopping sand or grit getting into the weave (though you need to do that with wire, too)

My Spectra is secured on the winch drum with several spare turns and a dodgy half-knot, which has held fast for much keel raising-lowering. I'm surprised your winch drum has a screw to secure the wire - is it screwed into a hole that goes through the drum? If you've got a hole all the way through the drum, you could remove the screw and do what I did - feed some strands through the hole and tie them off to the line (hence the dodgy half-knot) then wind on a few spare turns. A splice would be much nicer, but beyond my skill-set, and the dodgy half-knot hasn't let me down yet.

That screw in the winch drum looks a liability with the wire because it will grind on the wire, or put a pressure-point on it, which will eventually fail. The Spectra will be far more forgiving in wrapping around/over the screw head, if there is no way to get rid of it.

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PostPosted: Feb 10th, '18, 15:14 
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As pointed out dyneema/spectra is slippery and difficult to knot but if you look at the anatomy of a brummel splice you will see it is quite secure and it is impossible to slip.
It could be utilised with Kimbos' idea using the loop to hold several wraps to build up a stopper, it could not 'unloop' itself.

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PostPosted: Feb 10th, '18, 16:39 
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I visited the chandlery this morning to intending to buy some 8 mm spectra as I wanted a line with a double braid cover to keep out some of the crap from the bilge. However I found it actually measured 9 mm and this would mean that I would just not get the turns I wanted onto the drum. So in the end I purchased 6 mm Dyneema. With a breaking strain of over 3000kg it should be sufficient :) and it means that I can get three of four layers easily onto the drum ensuring that the line is secure.

In the end I partially followed INMA's suggestion. (Thanks mate!). I drilled a hole right though but I also drilled out a relief for a stop knot.

I made a simple jig so I could align it square and measure accurately to ensure that I missed the centre shaft.
I then drilled though on a drill press starting with a pilot hole and an extra long drill bit.

Whilst it had it in the press I drilled a larger recess to accommodate the knot. However this is when I made a boo boo in my excitement. :? It was all going well when I realized that I had intended to put this at the other end of the hole in order to have a 'fairer' lead onto the drum because the line rolls onto the drum clockwise when viewed from the gear side. Rats....it meant that I would need to put more relief onto the rope exit hole.

I also cleaned up the drum with some wet and dry paper to ensure that there were no sharp bits to catch the line, particularly on the drum cheeks and around the original threaded hole.

Next job is to sort out the blocks and sheaves.

Attachment:
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PostPosted: Feb 11th, '18, 18:29 
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Kimbo wrote:
I visited the chandlery this morning to intending to buy some 8 mm spectra as I wanted a line with a double braid cover to keep out some of the crap from the bilge. However I found it actually measured 9 mm and this would mean that I would just not get the turns I wanted onto the drum. So in the end I purchased 6 mm Dyneema. With a breaking strain of over 3000kg it should be sufficient :) and it means that I can get three of four layers easily onto the drum ensuring that the line is secure.

In the end I partially followed INMA's suggestion. (Thanks mate!). I drilled a hole right though but I also drilled out a relief for a stop knot.

I made a simple jig so I could align it square and measure accurately to ensure that I missed the centre shaft.
I then drilled though on a drill press starting with a pilot hole and an extra long drill bit.

Whilst it had it in the press I drilled a larger recess to accommodate the knot. However this is when I made a boo boo in my excitement. :? It was all going well when I realized that I had intended to put this at the other end of the hole in order to have a 'fairer' lead onto the drum because the line rolls onto the drum clockwise when viewed from the gear side. Rats....it meant that I would need to put more relief onto the rope exit hole.

I also cleaned up the drum with some wet and dry paper to ensure that there were no sharp bits to catch the line, particularly on the drum cheeks and around the original threaded hole.

Next job is to sort out the blocks and sheaves.


A very well thought out project, Kim. Looks like a good result.

As you know, my UY18 is a swing keeler and I've never looked back since changing the keel wire to spectra.

Peter
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PostPosted: Feb 14th, '18, 09:10 
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Thanks Peter. I'm pretty happy so far.

I'm still very interested to hear details from any other Ultimate drop keel owners who have had keel cable failures or near failures.

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