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anchor rode off bowsprit block?
Posted by: paul.silverman@umontana.edu (IP Logged)
Date: December 20, 2018 06:58PM
Category: Anchors, rodes and ground tackle

I've owed a BCC28 for about two years, purchased in Seattle and trucked to Flathead Lake in Montana. The boat had about 250 feet of chain and a heavy CQR on a roller at the bow. Winching it up can be difficult (with a manual windlass) and I thought another rode would be useful in any case if she ever returns to the coast. So I added a second rode of 200 feet of 3/4 inch line attached to 30 feet of chain which I now use. When anchored, of course the rode rubs against the bobstay. I'm thinking of adding a snatch block on the bowsprit end for the rope rode, to be used after the anchor is dropped (any suggestions about make and size?). But what to do about getting the chain rode out beyond the bobstay other than a roller there? Has anyone dealt with this?

Re: anchor rode off bowsprit block?
Posted by: Bil (IP Logged)
Date: December 20, 2018 11:22PM
Category: Anchors, rodes and ground tackle

Taking the rode, whether rope or chain, to a block or roller attached to the cranse iron has the disadvantages of (a) reducing your anchoring scope; and (b) adding mass to the extremity of the bowsprit.

Remember that anchoring scope is the ratio between the length of your anchor rode and the sum of water depth plus height of anchor roller (or block) above water.

And remember that adding mass/weight to the extremities of a boat (the bow, the stern, the masthead) is usually a bad thing.

I suggest two alternative approaches:

* a forward anchor roller, placed a little way further out on the bowsprit; and/or

* a snubbing line, primarily designed to absorb snubbing shocks in the anchor rode, of a stretchy cordage such as 3-strand laid nylon rope of a relatively thin diameter, made to the anchor rode and through either:

- a block attached to the cranse iron; or

- a block attached to the bobstay fitting.

On Zygote, we have a set of forward anchor rollers on the bowsprit, set a little forward from the stem. Double rollers - port side for the hawser rode (usually only used for the kedge anchor) and starboard side for the chain rode.

Then we have a block attached to the bottom lug of the cranse iron. Through that block runs a 3-strand nylon snubbing line (about 8.5 mm diameter, working on the rule that a snubbing line should be of diameter in millimetres about the LWL of the hull in metres). We usually anchor Z using her chain rode, so the inboard part of the snubbing line is made by cleat hitch around the stbd midships cleat. That snubbing line runs forward along the deck and turns around the block pendant to the cranse iron and then (when sailing or docked) runs back inboard so its distal end is made lazily to the starboard bitt.

Our practice on Z is to set anchor (including power setting with the engine) and then hitch the distal end of the snubbing line to the chain anchor rode. Then I run out more chain so the snubbing line holds the chain - with the hitch above the water so I can see it and so the nylon stays relatively dry (remember that nylon stretches and loses a little strength when wet) - with a loop of chain hanging between the for'd anchor roller and the hitch.

Snubbing lines are usual on an all chain rode. No reason you cannot or should not use a snubbing line on a hawser rode. On a hawser rode, a snubbing line can remove chafe (such as from the bobstay).

The life of a snubbing line is relatively short. On Z, we replace our snubbing line after about 100 - 150 anchorings. The nylon work hardens and loses its stretch. One way of prolonging the life of a snubbing line is to add a rubber mooring snubber block, of course.

And of course having a block at the cranse to turn 8 mm nylon snubbing line means a lot less mass at an extremity than a block that would turn a 16 mm anchor hawser (on Z, the hawser rode of our small bower is 5/8 inch laid nylon, which is about 16 mm). And a block to turn 8 mm line is much less precious/expensive a chunk of boat jewellery than one to turn 16 mm line!

To deal with the problem of reducing anchoring scope by raising the point of attachment, some skippers much prefer to use a turning block for the snubbing line attached to the bobstay fitting. That works too. Just means that the turning block needs more frequent maintenance, especially if you're sailing in saltwater.

To return briefly to the question of the utility of forward anchor rollers on the bowsprit: if we've just anchoring for lunch, or are anchoring in conditions guaranteed to be free of wind changes, current changes, or wind against current interaction, then we may anchor just using the forward anchor roller and not deploy the snubbing line.



Edited 1 times. Last edit at 12/20/18 11:28PM by Bil.

Re: anchor rode off bowsprit block?
Posted by: paul.silverman@umontana.edu (IP Logged)
Date: December 22, 2018 08:55PM
Category: Anchors, rodes and ground tackle

Thanks so much, Bil, for your description. I do have some follow-up questions. (1) If I attach a snubbing line to the hawser rode, in order to keep the hawser rode forward of the bobstay, what attachment knot do you recommend? Rolling hitch? (2) Its not clear to me what you mean by "the block pendant." (3) About the "turning block attached to the bobstay fitting" are you talking about a standard block that attaches to the fitting at the waterline? (3) Finally, I take it that you do not use a snatch block since the set up is more or less permanent/ Correct?

Re: anchor rode off bowsprit block?
Posted by: Bil (IP Logged)
Date: December 22, 2018 09:52PM
Category: Anchors, rodes and ground tackle

> (1) If I attach a
> snubbing line to the hawser rode, in order to keep
> the hawser rode forward of the bobstay, what
> attachment knot do you recommend? Rolling hitch?

I use a rolling hitch on Z's anchor chain. I think a rolling hitch on the hawser rode would work just as well. It's a simple enough complication to make when you're fatigued and working on the bow.


You can add an extra hitch for security. When very new and still carrying the various coatings from the manufacturer, your hawser and your snubbing line might present low grip to each other such that a rolling hitch might slip. That's when a extra turn in the initial part of the rolling hitch and an extra half-hitch in the latter part might be useful.

I note the new fashion for using soft shackles, made from high modulus polyethylene small stuff (Dyneema etc). I think soft shackles might be preferable to a chain hook, but I've no personal experience yet. I dislike chain hooks.

> (2) Its not clear to me what you mean by "the
> block pendant."

"pendant to the cranse iron" means to me the same as "dangling from the cranse iron" or "hanging by a shackle from the cranse iron".


>(3) About the "turning block
> attached to the bobstay fitting" are you talking
> about a standard block that attaches to the
> fitting at the waterline?


Yes. That location at the waterline means such a block needs more maintenance than a block pendant to the cranse iron.


>(3) Finally, I take it
> that you do not use a snatch block since the set
> up is more or less permanent/ Correct?

Yes. I aged and lost any joy that might ever have been gained from demonstrating my agility working on the end of the bowsprit even in a sheltered anchorage.

Re: anchor rode off bowsprit block?
Posted by: paul.silverman@umontana.edu (IP Logged)
Date: December 22, 2018 10:02PM
Category: Anchors, rodes and ground tackle

Thanks again Bil. At 70 years old, I agree. End of bowsprit can be precarious. I've rigged good bowsprit netting and a down haul that helps.

Paul

Re: anchor rode off bowsprit block?
Posted by: Bil (IP Logged)
Date: December 23, 2018 07:05AM
Category: Anchors, rodes and ground tackle

Paul: Hi!

I've failed to find a photo of Z's swivel block through which her snubbing line runs.

I know I've also diagrams (from either Larry Pardey or Roger Olson) showing both arrangements: with a simple turning block at the bobstay fitting; and with a swivel block suspended below (or pendant to, if you prefer 18th century English) the cranse iron.

On the latter of those arrangements, I have found one of The Master's (Roger D Olson, former master of BCC Xiphias, Seraffyn, and BCC Nereus, designer of the Cherub dinghy, and a former president of Sam L Morse Co) pedagogic diagrams. See RDO - Anchor snubbing for BCC - 1994.jpg, about 300 Kcool smiley.

You'll see that Roger recommended a swivel block at the cranse, a rolling hitch or chain hook at the distal (or outboard) end of the snubbing line, and making the proximal (or inboard) end of the snubbing line around a bitt.

I recommend a snubbing line of 3-strand laid nylon with a length in metres equal to the hull length (about 8.55 metres) and a diameter of that length in millimetres (so about 8.55 mm).That diameter means the line is elastic. And the length means you have enough nylon to absorb shock forces, plus enough to make a cleat hitch.

I recommend making your snubbing line to the midships cleat, not the bitts, with a cleat hitch. That allows you to adjust the length of the snubbing line easily.

That also means that the taut snubbing line is a danger on deck. But it's only on one side.

BCC 116 Zygote,
Scarborough Marina, Moreton Bay, Queensland, Australia



Edited 1 times. Last edit at 12/23/18 08:18PM by Bil.

Attachments: RDO - Anchor snubbing for BCC - 1994.jpg (296kB)  
Re: anchor rode off bowsprit block?
Posted by: svshaula (IP Logged)
Date: December 28, 2018 10:53PM
Category: Anchors, rodes and ground tackle

Over the years (37), we’ve used most of the methods that Bil describes. Two anchors on the bow of a BCC is not necessary and has a significant effect on sailing ability, especially in significant seas. Although we started with a rope rode with about 50’ of chain, we soon switched to all chain and a 35# CQR. The chain had its 4th regalvanizing last winter. This combo has served us well across the Pacific as well as here in the Pacific NW. Here we sometimes anchor in deep, rocky areas where a line ashore is needed in order to prevent currents or breeze pushing us away from shore and into deeper water. This only works when the winds are not strong. We always use a snubbing line tied to the chain with a rolling hitch and tied to one of the bits.

We have a length of pvc that protects the bobstay wire from chaff from the chain. I put it on when I replace the bobstay 3/8” wire, using Norseman end fittings. This would be a big help if using a rope rode. I suppose the pvc could be replaced by a wood split wood piece, wired together in a few places?

I highly recommend the placement of a second set of anchor rollers on the bowsprit forward of the stem. We used Roger Olsen’s drawing and had it constructed in Gladstone, Australia in stainless. The rollers are on a rod that passes under the sprit so that no horizontal hole is drilled in the sprit. It keeps the anchor from swinging into the stem as it’s raised and dinging its gelcoat. The CQR sits securely on this forward roller.

I have sometimes fastened a heavy snatch block to the cranse iron and led a spring line from the chain back to the bits. This reduces yawing somewhat if we’re anchoring (or tied to a mooring) in strong winds.

Re: anchor rode off bowsprit block?
Posted by: paul.silverman@umontana.edu (IP Logged)
Date: December 29, 2018 06:37PM
Category: Anchors, rodes and ground tackle

Thank you!



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