Typhoon Mooring Pennant?
Moderator: Jim Walsh
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Appleton68
- Posts: 85
- Joined: Feb 9th, '05, 09:41
- Location: Typhoon Weekender Boston, MA
Typhoon Mooring Pennant?
I have a Typhoon Weekender which is kept on a mushroom mooring, mud bottom. While I own the mooring, chain, etc. it is serviced by a mooring company. It seems to me the boat has a "hobby horse" motion even in mild wind/seas while @ the mooring. I am thinking the mooring pennant is too short. Is there a recommended or preferred length? TY
Greg
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Oswego John
- Posts: 3535
- Joined: Feb 5th, '05, 20:42
- Location: '66 Typhoon "Grace", Hull # 42, Schooner "Ontario", CD 85D Hull #1
Pennant Length
In a well organized mooring field, the most importanr key word is uniformity. A harbour master or fleet captain tries to separate different classes of boats as a group. Sailboats together if possible and power boats in their own area.
Smaller boats moor in shallower water and larger boats with deeper draft moor in deeper water. With variances in wind and current, some boats swing at mooring differently than other types do.
As mentioned earlier, the uniformity of the total lenfth of the rode and pennant from the mushroom to the stern of the boat must try to be the same for all boats in the pattern. Some refer to this length as the radius of swing, no matter which direction the wind is coming from. Be very careful if you alter this radius in a tightly packed mooring field.
To answer your question, in my personal estimation, an 8:1 scope is desirable. (Lots of luck getting it in a busy mooring field. Especially in close.)
While I'm on my soap box, I might as well throw in a little bit more controversy, purely arbitrary. One of the major ulcer producing headaches for a harbour master is the boatowners random choice of length as well as the material used in his mooring rode.
You can readily see how the length or radius could cause boat contact with other moored boats. But the killer is the choice of the composition of the rode. Some boaters use all chain, some use half chain and half line while others use all line. Add to this mish mash that small boats use very heavy chain when not needed while larger boats skimp on the cost of adequately sized chain. In one compacted mooring field, there could be dozens of types of rodes employed.
What happens, when a strong enough wind prevails, things seem to work out smoothly, all radii being equal. However, when the wind diminishes and swings around, the boats with all line rodes swing accordingly. Not so with the boats with an all chain rode. The weight of the chain becomes the anchor, far removed from its mushroom. The boat will swing above the point where the end of the extended chain lays, with little or no radius. This problem is greatly magnified at low tideoffs.
For the above reasons, it is best to check with your harbour master or fleet captain before you take it upon yourself to change anything concerning your mooring. This is for your and your neighbors boat's welfare.
O J
Smaller boats moor in shallower water and larger boats with deeper draft moor in deeper water. With variances in wind and current, some boats swing at mooring differently than other types do.
As mentioned earlier, the uniformity of the total lenfth of the rode and pennant from the mushroom to the stern of the boat must try to be the same for all boats in the pattern. Some refer to this length as the radius of swing, no matter which direction the wind is coming from. Be very careful if you alter this radius in a tightly packed mooring field.
To answer your question, in my personal estimation, an 8:1 scope is desirable. (Lots of luck getting it in a busy mooring field. Especially in close.)
While I'm on my soap box, I might as well throw in a little bit more controversy, purely arbitrary. One of the major ulcer producing headaches for a harbour master is the boatowners random choice of length as well as the material used in his mooring rode.
You can readily see how the length or radius could cause boat contact with other moored boats. But the killer is the choice of the composition of the rode. Some boaters use all chain, some use half chain and half line while others use all line. Add to this mish mash that small boats use very heavy chain when not needed while larger boats skimp on the cost of adequately sized chain. In one compacted mooring field, there could be dozens of types of rodes employed.
What happens, when a strong enough wind prevails, things seem to work out smoothly, all radii being equal. However, when the wind diminishes and swings around, the boats with all line rodes swing accordingly. Not so with the boats with an all chain rode. The weight of the chain becomes the anchor, far removed from its mushroom. The boat will swing above the point where the end of the extended chain lays, with little or no radius. This problem is greatly magnified at low tideoffs.
For the above reasons, it is best to check with your harbour master or fleet captain before you take it upon yourself to change anything concerning your mooring. This is for your and your neighbors boat's welfare.
O J
"If I rest, I rust"
Voting Member #490
Voting Member #490
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Appleton68
- Posts: 85
- Joined: Feb 9th, '05, 09:41
- Location: Typhoon Weekender Boston, MA