Sea Anchor

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mdonnelly

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Went out yesterday with my old mate Bill on his Tomohawk 25 to try his new sea anchor. We had purchased one from Lalizas of the correct size for his boat. Yesterday was blowing a Force 4 so we thought we would get a good result. We had expected the anchor to cause the boat to come nose to wind but instead it remained beam on. We deployed it with only 100 feet of warp as it was all we had on board. The recommended scope was 125 feet. Any thoughts as to what was wrong or were we expecting too much? Is the shorter scope that significant? Thanks
 
I'll be interested in the answers to this - as so many boats (including ours) have more windage at bow than stern they naturally want to have stern up to the wind. So at anchor they veer from one side to the other until stopped short at each extreme - and that can't really happen with a sea anchor as it will just start moving faster through the water.

I personally doubt 100 feet versus 125 would make a difference. What speed was the boat going through the water at?
 
It is a sea anchor - designed to reduce the speed of drift, not necessarily to hold the bow into the wind.

PBO did a review of a range of such devices a few months ago and made a clear distinction between anchors and drogues and their deployment to achieve different objectives.
 
mdonnelly said:
This one is marketed as a sea anchor drogue!
Click to expand...

What your old mate Bill has there is a drogue which is designed to be deployed over the stern when running. The sea-anchor or parachute-anchor is much much larger & is deployed over the bows.
 
What is its diameter?
If it is up to a couple of foot or so and shaped like a wizards hat it's a drogue, if it is a couple of yards or so and more parachute shaped it's a sea anchor.
Note: description and size is approximate and as they say, other shapes are available!
 
Most of the classic old books I've read mention boats lying at best 45 degrees to sea anchors, even in gales; one supposed solution is steering warps to the sea anchor from each stern quarter of the boat to the sheet winches - as well as the main warp from bow to anchor.

Then one can drag the stern round to help her lie a bit more head to wind.

I have never tried this, and must say it sounds like a recipe for a bugger's muddle of lines, but some say it works.

As mentioned, almost all boats tend to have the bows blow downwind, so I can't help thinking really strong washboards, maybe with an ultra strong dodger ( like a mini version of the Cape Horn wheel shelters on some square riggers ) and trail the thing from the stern may be an idea if one is able to set up for it way before needed, probably at the pre-launch planning stage.

A ' drogue / sea anchor ' from the bow must be worth a try when the chips are down for ' normal ' coastal cruising boats, to avoid drifting to leeward too quickly - and they have a hopefully more common use in better conditions - on boats like mine which ' sail the anchor ' in light wind over tide conditions, a drogue of some kind over the stern keeps the boat streamed downtide of the ( ground ) anchor, preventing the keel wrapping the warp / chain as the tide turns.

That method does extend the boat's swinging radius to max, and increase pull on the ground tackle though so it's a matter of judgement.
 
If you don't want to be beam on, then If you put a riding sail on the backstay tied with the front pointy bit tied to a stanction each side it will bring you up to wind at an angle of about 35 degrees to the wind . Be careful if the boat has a spade rudder it can be torn off if the boat starts going backwards. This is an example of a riding sail but it's too big for the boat size so you would need to find a smaller one or cut down the Sailrite one: http://www.sailrite.com/Anchor-Riding-Sail-Kit-12-5-Sq-Feet. Our boat was 38 feet so a 25 feet boat would need to the riding sail to be 65% of the size of the Sailrite one which we used.
 
Seajet said:
Most of the classic old books I've read mention boats lying at best 45 degrees to sea anchors, even in gales; one supposed solution is steering warps to the sea anchor from each stern quarter of the boat to the sheet winches - as well as the main warp from bow to anchor.

Then one can drag the stern round to help her lie a bit more head to wind.

I have never tried this, and must say it sounds like a recipe for a bugger's muddle of lines, but some say it works.
Click to expand...

If the boat won't lie straight downwind of a drogue streamed from the bow alone, I can't see how lines from anywhere else on board would help it do so.

The Pardeys were fans of a similar stern line, but that was to deliberately put the boat almost beam-on so that as it slid to leeward it left a big "slick" upwind of the long stalled keel. They said the slick caused approaching waves to lose their power before hitting the boat.

Not many other people recommending this technique, but Lin and Larry insist it works for them.

Seajet said:
As mentioned, almost all boats tend to have the bows blow downwind, so I can't help thinking really strong washboards, maybe with an ultra strong dodger ( like a mini version of the Cape Horn wheel shelters on some square riggers ) and trail the thing from the stern may be an idea if one is able to set up for it way before needed, probably at the pre-launch planning stage.
Click to expand...

Yep, that's pretty much the idea of the Jordan Series Drogue, though that has a long series of smaller cones instead of the single one which can escape from the the face of a big wave and gives a jerkier pull because it's either inflated or not. The Jordan system is supposed to give a smoother constant pull, but the general principle of hanging the boat by the stern is the same. A boat moving forward is safer from being thrown back onto its rudder and breaking it.

Pete
 
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