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  #1  
Old 05-30-2007
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Rule of thumb for mooring pennant length?

For those of you with sailboats with a bowsprit and bobstay/dolphin striker, what's the optimum length you've found for your mooring pennants and for your snubbers for all-chain rode? Is there a rule of thumb for pennant length based on the location of your bow chocks (hawse holes in our case)?

My Formosa 51 has a 6' bowsprit, and has a bobstay stood off a dolphin striker. The striker was popped off last fall during a Nor'easter from a combination of wave action and the boat twisting the mooring pennants tightly while spinning around the mooring with the flood/ebb currents in the harbor.

The bow "chocks" (hawse holes) are located about 30" or so back from the point where a line extended along the axis of the striker would penetrate through the anchor pit as indicated in the image below:



[IMG]http://http://www1.snapfish.com/viewsharedphoto/p=707301180539409786/l=248861195/g=12204408/cobrandOid=1000131/otsc=SYE/otsi=****[/IMG][IMG]http://www1.snapfish.com/viewsharedphoto/p=707301180539409786/l=248861195/g=12204408/cobrandOid=1000131/otsc=SYE/otsi=****[/IMG]
Is there a science to figuring out the optimum length, or just eyeball it? We're getting ready to launch after an extensive refit over the winter, so I need to spec the pennant length. Would 18' each be enough? 2.5 times the distance from the end of the bowsprit to the hawse holes? Any "formula" recommended?
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Old 05-30-2007
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I'd think you might want a bit longer a set of mooring pennants or anchor bridles. Given the height of the freeboard of your boat, and the distance the hawse holes are set back from the bow, it might be wiser to go longer, rather than shorter, since you need to clear the bobstay.

While I don't know your particular boat all that well, I'd guess that you have at least five-to-six feet of freeboard at the hawse holes... and given that you'll need at least three-to-four feet to make fast the pennants to the boat, that only leaves you about 12' or so of usable length. Subtract another two feet for making fast to the mooring ball... you're down to 10', and given the 5' of freeboard, that means you're only 8' or so forward of the hawse holes horizontally, which puts your bobstay pretty close to the mooring ball.

In the case of a snubber for an all-chain rode... going longer is a necessity IMHO, since you can then let out additional scope without having to retract the chain in order to detach the snubber and then re-attach it after releasing more chain. If you're ever in a situation where you think more scope is needed, the last thing you want to have to do is worry about detaching and re-attaching the snubber.
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Old 05-30-2007
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Ordinarily, a 15-18 foot pennant ought to be plenty. The mooring system itself should have all the required scope, so don't think of the pennant as a way to add scope. A longer pennant isn't necessarily better, and ultimately the length of your pennant will be constrained by the amount of swing room available in the mooring field.

What concerns me more is that you seem to imply that you use two pennants simultaneously. In my opinion that is inadvisable, and is what caused you to lose the dolphin striker last year. Twin pennants, whether used independantly or in combination with a bridle, tend to get wound up and fouled, resulting in chaffing and binding.

On our boat, as is customary in my region, we use a single pennant through either the port or starboard hawse hole (we do not bring the pennant through the centerline anchor roller.) The boat rides ever so slightly off center on the mooring, which keeps it more stable in the wind and makes it much less prone to "sail" back and forth at the mooring. The key is to right size the diameter of the pennant. For your boat I'd use a single 3/4-1" Yale premium mooring pennant.
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Old 05-31-2007
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John,

I'm not implying - I'm stating it Virtually every boat I've seen throughout the Northeast (LIS, Buzzards Bay, Mass Bay) hanging on a mooring uses two pennants, so I'm following the norm here. I grew up boating inland in Louisiana and Texas where moorings are non-existant, and when in Connecticut my older boat was in a slip - so I've only really done 'serious' mooring the last 7 years, so I guess you can say I'm a relative noob in that respect. Slips are a rare commodity here in Marblehead and Salem Harbors north of Boston.

The one time we were on a guest mooring with a single pennant, I found out that the boat sails very aggressively, even with a stub of the mizzen up as an anchor riding sail - just exactly the opposite of your boat. In 25kts of wind, I was worried her 26 tons would make short work of the mooring's ground tackle.

I just found this document from INAMAR, and it calls for primary and safety pennants, with the safety pennant being the longer of the two. Funny thing is, they state if was Marblehead, MA who came up with that recommendation - that's my home port and I can't remember seeing any mooring in Marblehead Harbor with pennants of different lengths! I guess it goes to show not everyone agrees to a single right method...

And the 18' feet I was thinking of was not to increase scope of the mooring's chain to the bottom, but to give better "scope" to keep it away from the dolphin striker. And for the snubber, I was thinking of placing a chain hook in the middle of 50' of 7/8" nylon and cleating off each end to create a bridle. That way I could vary the length as conditions dictate and to spread out chafe (in addition to chafing covers, btw).

Rick - I've seen both terms used roughly equally. In fact, I called them "pendants" until I was corrected by a crusty old salt!
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Old 05-31-2007
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2 pennants is standard in my area of New England. Mooring balls come with one, but the vessel is expected to provide the 2nd. A few years ago we had a few boats lose their mooring (chafe - neglect) and sweep through the field. People were pissed. The marina now supplies 2 pennants on each ball and passes the extra cost along in the mooring fees. Pennants are equal in length. This has more to do with negligent owners than seamanship. With equal length pennants, the load does transfer from side to side which actually helps reduce swing. Yes - they do get wrapped but chafe guards protect the critical spots and I assume someone is checking the boat weekly so I wouldn't worry.

The safety pennant of longer length sounds more like a storm pennant where it is a temporary back-up. Marina will put them on when a blow is coming.
My everyday pennant is 2/18' of 3/4".

Some fields are set up with single chain moorings, which do provide some extra scope, but other fields use a 3 point mooring and the only slack is to accommodate tide. Best to ask what the set up is.

Jon - I don't know any formula other than more is typically better. In my marina, they have us packed in (if the guy on the mooring has his dink tied off the stern, you could not fit between him and boat behind) and specific moorings will only accommodate specific length of boat. I would look at adding a new chock or fairlead further forward specifically for mooring to try and keep pennant up and away from striker.
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Old 05-31-2007
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This does not directly relate to a boat as large as yours, but for those with smaller boats with bowsprits: The bowsprit makes a good "hold-off" pole for the buoy. I have some very heavy duty shock cord attached to the top of the buoy that I clip to an eyebolt at the end of the sprit. The shock cord holds the buoy away from the bow so that the boat does not ride up on it when a power boat passes by or when there is no wind. The cord does not take any of the load of the boat; it stretches and lets the pennant do its job.
I use a primary pennant and a longer secondary "safety" line that also serves as the pick-up line. They always used to twist around each other if left on their own for a few days. Never twisted again after I added the hold-off shock cord five years ago.

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Old 05-31-2007
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Quote:
Originally Posted by jonlgauthier
And for the snubber, I was thinking of placing a chain hook in the middle of 50' of 7/8" nylon and cleating off each end to create a bridle. That way I could vary the length as conditions dictate and to spread out chafe (in addition to chafing covers, btw).
As I said previously I would go a good deal longer on the snubber, since you probably don't want to have to retreive the anchor chain to remove the chain hook to let out more scope in a storm. I would make the snubber a minimum of 50' long working length, which means a minimum of 100' of rope.
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Old 06-01-2007
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Regional differences are interesting. We are on the Chesapeake. Based on their experience over the years with pennant failures caused by chaffe in two-pennant systems or by bridles, our marina specifically asks that boats on moorings use a single pennant. In Annapolis Harbor, the moorings are similarly configured with a single beefy pennant.

I was skeptical at first, but after a decade of safely mooring our boats like this, I'm pursuaded. Accounts from relatives and friends in New England waters suggest they are always battling chaffe and twist, and frequently need to renew their pennants despite the short season. Granted, the Chesapeake is a generally more sheltered region than the rugged coast of New England, but our boat is in the water year-round and our pennant only gets replaced when the cover begins to show signs of UV degradation -- not because of chaffe.

The INAMAR document is a bit ambiguous, but seems to suggest having the boat ride to a single pennant with another safety pennant as a back-up. I would just right-size the single pennant for the majority of conditions and have a super beefy storm pennant that I could swap when the big storms threatened. When Hurricane Isabel hit the Chesapeake a few years back, there was a fair bit of damage to boats on the bay. A retrospective article by BoatUS Insurance Group featured our marina prominently for the LACK of damage that occurred to boats moored there -- on single pennants (of course, they upped our insurance rates anyway!).

I have found the best prices and variety of sizes for Yale premium mooring pennants at Hamilton Marine in Maine (available on-line). They will even make a custom size for you if they don't have what you need in stock. Upon further reflection, you probably want a pennant well upwards of 1" in diameter for such a large boat as the Formosa 51. (1.5" ??)
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Old 06-01-2007
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Part of what I was thinking is that the hawse holes are really for docking lines, not mooring. The mooring line needs to feed as the anchors do - much further forward and higher. With a single pennant, you will still swing and put pressure on the cable above striker but hopefully you can greatly reduce the strain.

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Old 06-04-2007
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Thanks for all the input, guys!

Looks like I'll go with two 20' pennants/pendants made of 1.25" line. I'll have to see if the eyes can pass through the openings for the twin bow rollers that the anchors are on further forward, but with a 45lb CQR and soon to be an 88lb Delta, modifications will have to be made - perhaps a second set of rollers midway between the bow rollers and the hawse holes?

I'll talk to a few old salts tonight - I'm helping with a USPS anchoring seminar tonight and tomorrow...
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