Bowsprit Kranzeirn to take anchor snubbing loads?

[atmarineservices]

Hi All, I am looking to get a anchor snubber out on the end of my sprit. The Boat is a Flicka 20 with a bobstay and whisker stays. I was curious about removing the pin in the toggle that attaches the bobstay to the kranze iron and replacing this with a shackle that has the same diamater pin as the toggle. (3/8") anyone out there want to take a stab at this idea? And of course, no liability !!! The bowsprit is fir, and just removed last winter and rebed, and oversized G10 backing plates installed. All sprit supporting stays are in GOOD condition, and led to chainplates with substantial backing plates. Any ideas floating around out there? Thanks!!

[Brion Toss]

Hello,
It's an obvious place for a snubber, and it is true that the snubber loads will be far lower than the bobstay loads when the boat is under way. But it is possible to load both the jibstay and the snubber simulaneously (imagine sailing off an anchor), and worse still the max snubber loads will tend to apply a lot of lateral torqueing force on the cranse iron, more than it was designed to take. And finally, even if the other objections were dismissable, I am just plain reluctant to hang two critical pieces on one lug. Better to drill and tap a padeye into the iron, or, if the lugs are big enough, drill a second hole behind a bowsprit shroud lug. Or something.
Fair leads,
Brion Toss

[Ian McColgin]

I most hesitantly disagree with Brion but perhaps I don't understand how Brion has in mind using the snubber. I have used two sorts of snubbers to the end of the bow sprit. One is a seperate line to a chain hook on an all chain rode. The other is simply a way to hold the other rope (after chain leader) rode.

Both utilize the same line with either the chain hook or a leathered large bow shackle put on the eye splice at the end. The line just leads through a shackle dangling out under the end of the bowsprit. Lots of ways to attach that. The line is long enough that when not in use it's secured with both ends to a lifeline abaft the stem. Once the anchor is down and about the right scope, we hook the snubber on and pull it ouf to the end of the sprit if using the rope rode. If chain, we have to ease the chain out at the same time.

With the chain rode, a little slack between the hook and the boat puts all the strain on the snubber, taking the shock out. With the rope rode, the snubber serves only to hold the rode out at the end of the bowsprit and the strain is on the rode at the bitts. I also use that snubber to hold the mooring pendent out.

The snubber is detached before breaking out the anchor both to ensure that the sometimes strong and perhaps unfair strain does not come on the snubber and to allow for smooth retrieval of the gear.

G'luck

[atmarineservices]

What Ian decribed is precisley what i had in mind. It is a snubber, that will take the rhode out to the end of the sprit. I know that this has the possibility of exerting an enormous lever action for whatever loads may be present. But this system should be fairly stout considering the loads envolved when sailing. I do know agree that adding a shackle to the bobstay clevis pin/toggle interface is putting a great deal of trust on a single casting with a 3/8" hole. How about getting a new casting made, with a larger bottom tang, and a seacond hole for this arangement? And of course keeping our behavior in check when it comes time to lift anchor. Also, I was going to use a rolling hitch around the chain, or rope rhode in place of the chain hook. Any more inout floating around out there? Thanks guys!!

[Ian McColgin]

I never experienced it as much of a strain onto the end of the bowsprit even in hurricane winds in the 80's with gusts high 90's. The down pull is modest as you'll have considerable scope. In the hurricane we rode in an little creek the anchor was actually up on land and in the most extreme moments the span of 200' was out of the water and about dead horizontal.

Where there was loading was some rather sharp side loading. When the wind dropped a bit between high gusts, Granuaile would surge ahead as the line's streatch contracted. She'd inevitably veer one side or the other till the rode snapped her around to the other tack. More stuff came loose in the cabin than ever broke adrift in tough sailing into violent short head seas! But even at that, the loading is not all that severe. Having seen chocks (albeit stupidly installed chocks on some production boats) ripped out due to side loading but the whole point of putting the rig out on the end of the bow sprit is to reduce that - and it does.

A snubber does not take the break-out strain, which can be rather severe.

[Brion Toss]

Hi again,
Nice to have a discussion on this, one of my favorite anchoring details. First, the length of the snubber is important, as too short a snubber means too little give, and thus shock loads that might break gear or tear out the anchor. 50ft is not too much, including material for a belay. That's one reason I like to lead it through a block at the end of the 'sprit, so you get the extra length back to the belay. And this way you can also adjust relative tension more easily.
Nylon Brait or similar is my preferred material for a snubber, because it absorbs energy better than other constructions.
And yes, the loads at the end of the 'sprit are lower than further aft, because you are working on a longer lever arm. Yawing is thus reduced, as well as pitching. And again, max loads are much lower than normal sailing loads, according to dynamometer tests done in a New England mooring field.
Building a cranse with a dedicated space for a snubber block is ideal, and while you are at it, be sure to optimize geometry relative to the jibstay, so that the vectors meet in the middle of the bowsprit, putting the cranse iron in pure compression.
Fair leads,
Brion Toss