Sailing on the hook

[Greg QS]

Morning all.
I have a semi displacement hull, 70,000 lbs and 61' (65 loa). In high wind conditions I have noticed I really sail on the hook. Normally in these conditions I am the only one there. Any Idea of how to combat the issue. Not looking to put out stern anchors. Its not uncomfortable at all. Just more concerned in a sudden storm and tight anchorage I could have a problem with other boats near me.

 

[rslifkin]

Boats sailing at anchor is generally caused by windage being too far forward relative to the drag in the water. A lot of the water drag comes from props and rudders, so the boat ends up trying to rotate around those, slides downwind at an angle until the anchor rode goes tight enough to pull the bow up into the wind, then it goes back the other direction.

Gusty conditions are usually the worst-case for sailing around at anchor, as the boat will stretch the rode tight in a gust, then spring forward as the gust drops, allowing it to swing more sideways to the wind and sail off rapidly when the next gust hits.

Hanging a drogue in the water off the bow can help by making it harder for the bow to move sideways. A second anchor on very short scope to let it drag and add some resistance can help as well, but be careful about what kind of bottoms you do that in. Adding windage further aft will also help. My boat became a bit better behaved at anchor after adding the dinghy davits. Having the full canvas up helps a bit as well, as it adds more windage aft to help the boat weather-vane into the wind.

 

[Mac2]

I have the same issue. Im 65 feet, full displacement, 90 ton. At 25-30 knots I start swinging pretty dramatically. There was one other boat in the anchorage, 150+ mega yacht, and it was doing the same thing. When it got up to 40 knots, I let out more 1/2 inch chain, about 400 feet in 40 feet of water. I thought the drag of the chain would help-nope. It was a comfortable ride, but unnerving when the chain became taunt at the end of the swing. I had about 35 feet of 1.25” samson double braid snubber line out, which helped absorb the swing. I’m a member of the site “Attainable Adventure Cruising”, which is geared towards sailors, but has numerous great articles that apply to all cruisers. Colin Speedie (pictured below) wrote an article with a solution. Summarizing, he uses a custom drogue with wire sewn into the mouth to hold it open and a fishing weight on the tail to keep in under water. It’s attached ahead of the snubber so it’s a meter under water when the chain becomes taunt. The weight is adjusted so as not to delay the drogue from switching directions, but not to light that it twists around the chain. I have this setup, but haven’t been able to truly test it yet.

 

[AnsleyS]

I would rather set another bow anchor to shorten the hunt of the boat. Two off the bow reduces your hunting a lot.

 

[Mac2]

I would NEVER put out two anchors. A couple tide turns and your rodes are tangled. My primary is 260 lbs and backup is 180 pounds. Good luck untangling those.

 

[AnsleyS]

I have never had anchor rodes tangle, just twist. I have two anchors, one sixty five pounder and the other eighty eight, each with 270 feet of 3/8th chain. When they are twisted, I just motor around them to untwist them and then haul them.

 

[mvweebles]

When I used to use Weebles as a training platform for 2-day close-quarter-maneuver classes, I was located at Clipper Cove in San Francisco. One of the concepts I'd demonstrate was to just let the boat drift in protected open water with no other effect but afternoon 15-20 knot winds. You'd think a boat would point-up to the wind like a weathervane on a barn. Nope - she'd lie broadside to the wind. Not sure why - maybe someone out there can explain, but clearly when anchored, a tension develops. Aerodynamics want the boat bow into the wind, hydrodynamics want the boat perpendicular to the wind. My interpretation is that 'sailing' at anchor is this tension playing out: boat tries to get perpendicular until the force of the wind overcomes and pulls through the eye of the wind and the dynamic reverses. I cannot explain why it never reaches equilibrium but rather just continues the fight. You can place some windage aft and tweak the dynamic but for the most part, the boat is going to sail at anchor.

Perhaps there's a scholarly physicist in the group who can explain better?

Peter

 

[rslifkin]

Basically boat wants to rotate to a position where the windage is downwind of the drag in the water. Think of a weathervane where the highest windage part stays downwind of the pivot point. Think of the center of resistance in the water as the pivot point for a boat.

In the case of my boat, it'll actually drift with the bow 10 - 20* downwind rather than beam to the wind as that's the angle where it balances.

At anchor, the game is a bit different, as the boat will try to drift downwind like it would naturally, but you also have the anchor rode trying to hold the bow up into the wind. The boat will still be able to yaw and move around some, but at some point, it's going to reach the point where the rode is pulling on the bow hard enough for the boat to get pulled head to wind, at which point the rode tension drops a bit and the boat can fall off on the other tack.

That's why the yawing angle tends to increase in gusty winds, as the variation in rode tension allows more movement. In a very steady wind (both speed and direction) the boat will tend to move less, especially if the wind is strong enough to keep a decent bit of tension on the rode (so the boat can't stretch and rebound as much).

 

[Mac2]

I have never had anchor rodes tangle, just twist. I have two anchors, one sixty five pounder and the other eighty eight, each with 270 feet of 3/8th chain. When they are twisted, I just motor around them to untwist them and then haul them.

I would never be that lucky, plus the thought of motoring around in an anchorage to untangle rodes is very unappealing. The swing is comfortable. My only consideration is the acceleration of the swing and concerns of yanking out the anchor at the end stop/yank point. Im fine in mud, but other substrates could be problematic.

 

[rslifkin]

My only consideration is the acceleration of the swing and concerns of yanking out the anchor at the end stop/yank point. Im fine in mud, but other substrates could be problematic.

Yawing does increase anchor loads, but it can be accommodated in anchor sizing and a good snubber setup also significantly cushions the load spikes.

 

[Mambo42]

If you have enough room to swing around I would not bother too much about sailing on the hook. For me it would be more worrysome if I would not sail on the hook while all the other boats do sail around. Then I have to start worrying about colliding into other boats.

 

[jleonard]

I always liked the change of scenery.

 

[Portage_Bay]

When I used to use Weebles as a training platform for 2-day close-quarter-maneuver classes, I was located at Clipper Cove in San Francisco. One of the concepts I'd demonstrate was to just let the boat drift in protected open water with no other effect but afternoon 15-20 knot winds. You'd think a boat would point-up to the wind like a weathervane on a barn. Nope - she'd lie broadside to the wind. Not sure why

It's been my experience that nearly every boat without way on and no anchor out will lie broadside to the wind. Not perfectly perpendicular to the wind direction, but nearly so. Some will lie with the bow up a bit towards the wind, some stern up. As you were no doubt demonstrating in your close quarters maneuvering it's good to know how your boat behaves in the wind. When possible don't fight it, use it.

 

[Shrew]

I would rather set another bow anchor to shorten the hunt of the boat. Two off the bow reduces your hunting a lot.

When you do this you cut your swing radius in half. This impacts every boat around you in a crowded anchorage. This is almost as bad as throwing out a stern anchor in the middle of an anchorage when nobody else is using a stern anchor.

Don't be THAT GUY.

 

[rslifkin]

When you do this you cut your swing radius in half. This impacts every boat around you in a crowded anchorage. This is almost as bad as throwing out a stern anchor in the middle of an anchorage when nobody else is using a stern anchor.

Don't be THAT GUY.

A second bow anchor on very short scope to reduce yawing won't shrink your swing radius in any significant way. We're not talking about a Bahamian moor here (which wouldn't reduce yawing anyway). The second anchor isn't intended to ever actually set, it's there to add resistance to the bow moving so the boat doesn't yaw as far or as rapidly.

Because of that, it makes you more friendly to anchorage neighbors. Boats that yaw and sail aggressively at anchor tend to take up more space, as you aren't moving in sync with your neighbors. The ideal case for minimal space required in an anchorage without stern anchors or shore ties is if everyone is on the same scope, able to swing, and all of the boats sit perfectly quietly with the bow into the wind. As soon as boats start fidgeting around, the required space between boats to avoid bumping into each other increases.

 

[Mako]

Colin Speedie (pictured below) wrote an article with a solution. Summarizing, he uses a custom drogue with wire sewn into the mouth to hold it open and a fishing weight on the tail to keep in under water. It’s attached ahead of the snubber so it’s a meter under water when the chain becomes taunt. The weight is adjusted so as not to delay the drogue from switching directions, but not to light that it twists around the chain. I have this setup, but haven’t been able to truly test it yet.

I really like that idea. When you get around to testing it also check its effectiveness attached to the transom versus bow. My thought is that there is more acceleration at the stern, more "whipping" action, so it might work better.

 

[rslifkin]

I really like that idea. When you get around to testing it also check its effectiveness attached to the transom versus bow. My thought is that there is more acceleration at the stern, more "whipping" action, so it might work better.

At the stern will slow the sailing motion, but it will make yawing worse, not better. You'd be effectively moving the pivot point aft, so the peak angle to the wind before the boat tacks back the other direction will increase.

 

[cafesport]

I’m surprised no one has mentioned keeping an anchor watch in such cases. Several times we have used our engines thrusters and radar to avoid issues with other boats dragging or swinging in strong winds.

 

[darkside]

Get a power cat. A wide separation of the bridle attachment points, one on each bow, works against the yaw as soon as it starts. Two long skinny hulls slows any movement with a good grip on the water. The boats that move the most seem to be SD with rope rather than chain over the bow.

 

[UALcaptain]

I intend to experiment this Spring with a steadying sail on our Grand Banks 42 - both at anchor, and underway in a beam sea (she sails around and rolls under these conditions). I've heard the comments that a sail will do nothing, but I'd like to try it out. Will report back.

 

[heysteve]

I've heard the comments that a sail will do nothing, but I'd like to try it out. Will report back.

Practical Sailer had an interesting article on "riding sails" here. We were on a ball once next to a Beneteau 46 that rigged a big V-shaped riding sail aft over the bimini. I'd say the yawing was reduced about 50% so it worked reasonably well. However, he was able to rig it far aft which is important for effectiveness.

I would say our boat has a moderate/typical yaw in high winds. We were in 50 kts when hurricane Hillery skirted by Baja. The motion actually wasn't that bad but it may have been because we store our dink vertically on the swim platform and that may have acted as our riding sail.

 

[SteveK]

I find less movement when using the bridle instead of single line, line on each cleat.

 

[darkside]

We left the mizzen up on my Dads launch, but more for roll than yaw. Yaw doesn't worry your sleep on a 39' boat that weighs 17t, the movement is quite dignified. The roll certainly wasn't.