Making a towing bridle

[RoyB]

I need to make a towing bridle for our boat (to be towed, not to tow others) - it's required for some ocean racing we'll be doing. I can splice 3 and 12 strand using several techniques so the required splicing doesn't trouble me but the basic design does.

The boat is a 38 foot offshore capable racing fractional sloop weighing 5800 kilos. There is a single cleat on the foredeck but I wouldn't trust it's strength or mounting for a tow.

The mast is keel stepped and very solid where it passes through the deck. There are 2 solidly mounted winches per side that could possibly be used. There are also 2 cabin top winches that are less solidly mounted - altho to be fair they're mounted well enough to tension 10mm vectran halyards to violin string tightness.

I'm thinking that I either need to fabricate a Y shaped bridle that connects to the main sheet winches using spliced loops and that has the 2 legs meeting forward of the bow so that the legs can pass through the pulpit.

The alternative is to make something in a Y shape that can be connected to the 2 ends of a heavy webbing strop that is wrapped around the mast several times. If I did this I could also wrap a line around the mast and lead each end back to the cabin top winches to stiffen the whole thing up.

Never having made one of these I'm worried that I'll make something pretty that won't work well at sea if we need it.

Who better to ask than the Spartalk crowd?

[Andrew Craig-Bennett]

One point to think very carefully about is chafe where the towing connection leaves, so to speak, the deck of your boat. Ocean going tugs invariably use high tensile chain at the point where the bridle exits the Panama fairlead of the towed vessel. The inboard end is set up either to a Smit bracket or AKD stopper if the tow has one or it is split into several tails and each tail is made up to a set of bitts. (Tug skippers invariably prefer the former, as bitts have been known to part company with the deck!)

A yacht has a forestay and usually some sort of bow roller fairlead. It's highly advisable to include in the set up a means of lashing the towline into the fairlead very securely, and a means of reducing chafe, eg by parcelling it, or by sliding a length of very tough flexible hose over the rope before making the final splice, assuming you are not confident of your rope to chain splices - if you are, that's ideal.

I like your "round the mast and backed up by winches" idea; it is simple to tension a rope from one winch, round the mast, and back to the other winch, to spead the load.

[Ian McColgin]

I'd use two lines with a hard thimbled eye in one end of each.

Essentially the lines are secured at the mast, pass out well chafe guarded through the chocks on either side, and are shackled to a larger shackle that can take the tow line. The rig should be long enough that you can easily attach the tow line from a safe place back on the foredeck and then pay it off.

How long depends on how you attach to the mast. I'd make long enough for three turns around the mast with each line, then each gets three loops of a tuggy's hitch and finish with a simple taughtline hitch as a keeper at the end. This arrangement will actually come undone without cutting line at the end of a long tow.

Big point is serious chafe gear.

The tow line should be long enough that it will not be leading up from your bow, but it may surge up if it's short enough that it's tight and proud of the water as you come over a crest and the bow plunges on the other side. For this contingency, you may need some sort of keeper to hold the line in the chock or, better yet, closable "panama" chocks.

G'luck

[Joe Henderson]

Dear Roy,

Both Ian and Andrew make very good points and their advice is sound, chafe will be your biggest problem.

My only reservation is about securing to the mast. In the old days a solid timber mast in a very thick deck was the idal place to secure a tow.

With ever lighter scantlings I worry about the ability of a modern boat to take these sorts of loads. The average fishing boat or commercial vessel will just put the thriottles to the firewall and go and the devil take the poor yacht on the end of the string.

I seem to remember a carbon mast and deck being badly damaged a few years ago by several turns of spectra line crushing it during a tow in admittedly very rough weather.

I remember a forestay being carried away by an usecured towline that jumped out of the inadequate bow roller fitted to most stock cruising boats and putting such a load on the forestay as the unattended vessel sheered about in the wake of the tow boat that it brought the rig down. They then had the added problem of a rig over the side, allowing not much progress to be made and in the end they had to cut the boat loose.

Due to the aforementioned and the sad inadequacy of stock cleats and fairleads on the majority of new boats , I would prefer to take twin lines with long soft eyes looped over both primary winches, to avoid over loading the pawls, forward through the genoa cars ,which are slid as far forward on their tracks as possible, then lashed to the forward mooring cleats/cleat then seized together or spliced together and out through a meaty fairlead. This does not neccesarily have to be on the centre line, close will do. Arrange chafing gear as required. Heavy hose if it will fit or thick chrome tanned leather if space is at a premium.
This arrangement feeds loads into the winches etc in the right direction.

You could maybe take a soft or webbing sling under the bow to hold the towline down.

In any case try it all in light conditions first.

Regards,
Joe Henderson.

[Renoir]

As was mentioned that chain is used inboard on a tug, you should use as large a diameter as possible double-braid polyester all the way until it passes your last fairleads, hopefully Panama chocks, as mentioned. If you do this and have carefully dressed your fairleads you will not have to rely much on overdoing it with anti-chafe gear. If you do this with nylon ultimately no anti-chafe gear will protect it and it will break just when conditions are the worst.

[Andrew Craig-Bennett]

I think Joe is right about crushing the mast. (I have a very old fashioned boat!)

[RoyB]

Thanks to all of you for sharing your knowledge.
The boat (an offshore racer) doesn't have any useful fairleads at the bow and If I install any I'd have to re-enforce the forward deck below (not to mention the bowman, who, while physically small is also very opinionated and a bit intimidating at times :-).
I'll organise some very heavy thick tubing as a chafe protector and hope for the best

[Ian McColgin]

I can't imagine a proper off-shore boat without proper bow gear, including proper chocks that keep the line captive in all direction.

The bridle will not work if it's not held at the bow. If the bridle is long enough that the join of the two parts is ahead of the bow, then the bridle will be laying against the headstay as the boat shears about, damaging both stay and bridle. Perhaps there's some other factor in the boat's layout I'm missing but this sounds sufficiently dangerous that I cannot imagine a committee certifying it.

By all means involve your bowman in the project - his life depends on that good working area - but he probably can get it that his life may well depend on the boat's ability to accept a tow.

Thoughts? One might think the chocks can be located a bit back and the bridle can be of such a length that the join can't get up over the stem. Not at all an option is the stem is steep to plumb. There are real problems with chocks mounted at a place on the rail so nearly parallel to the direction of the line, so much so that some lines of boats put their mooring cleats on the rail a bit abaft the stem, another practice that shows a reckless disregard of safe mooring, anchoring or towing.

Real life, a 40' modern sloop was lost a few years back in Hyannis Port just this way. The mooring pendent went to cleats on either rail about 6' abaft the stem. The whole unit was well chafegarded - so well that the bridle bearing on the bow didn't even marr the paint. Yet in a sustained storm the bridle got over the stem and tore against the stemhead fitting. The bridle put an unfair strain on the headstay leading to turnbuckle failure before the eventual chafe-through led to the boat on the beach.

So, work it out right.

G'luck