Anchoring - Page 2

SeaSkills · 04 February 2008, 07:09

Quote:

Originally Posted by codprawn

I also carry a sea anchor - anyone else carry them? I purchased on designed for 15m yachts but it's so small when rolled up it's not a problem. Have yet to use it though!!! Can also be used as a drogue.

Yes, I have a sea anchor and use it regularly

If you've got a sea anchor big enough for a 15m yacht, it will probably not make a good drogue.

For those readers who may not understand the difference, a sea anchor is like a big parachute that is designed to hold the front of the boat into the waves while it stops the boat being blown by the wind when in too deep water to drop an anchor line to the sea bed. A drogue on the other hand holds the back of the boat to the waves and is intended to slow a boat down in order to stop it sufing or broaching (not usually a problem for powerboats unless the boat has lost power for some reason). A specially designed drogue is less like a parachute, more like a windsock that you'd see at an airfield, with a hole at the end. Streaming warps or anything else to create a bit of drag and steady the back of the boat is often at least as effective as a drogue, but there isn't as effective a substitute for a sea anchor.

Nick Hearne · 04 February 2008, 08:00

Quote:

Originally Posted by SeaSkills

Yes, I have a sea anchor and use it regularly

If you've got a sea anchor big enough for a 15m yacht, it will probably not make a good drogue.

For those readers who may not understand the difference, a sea anchor is like a big parachute that is designed to hold the front of the boat into the waves while it stops the boat being blown by the wind when in too deep water to drop an anchor line to the sea bed. A drogue on the other hand holds the back of the boat to the waves and is intended to slow a boat down in order to stop it sufing or broaching (not usually a problem for powerboats unless the boat has lost power for some reason). A specially designed drogue is less like a parachute, more like a windsock that you'd see at an airfield, with a hole at the end. Streaming warps or anything else to create a bit of drag and steady the back of the boat is often at least as effective as a drogue, but there isn't as effective a substitute for a sea anchor.

Sound like I was mis sold my sea anchor as I have one of these!
http://www.compass24.com/watersports...rnliste=614102
Never had to us it (yet)!

SeaSkills · 04 February 2008, 10:08

It will probably work fairly well for you Nick, but not as effectively as one like this .. http://www.rfd.com.au/products/defau...CategoryId=686

Might be worth giving it a try on a blowy day before you need it for real. Experiment with the best length of line to use, and the best way to recover it (you'll either have to haul the boat back up to it, or have a tripping line to capsize it)

codprawn · 04 February 2008, 11:10

I also have the windsock type. yes those aussie parachutes are the business but remember a RIB is a little lighter than a deep keel yacht and has less windage...........

SeaSkills · 04 February 2008, 12:14

Quote:

Originally Posted by codprawn

I also have the windsock type. yes those aussie parachutes are the business but remember a RIB is a little lighter than a deep keel yacht and has less windage...........

Try parking a RIB next to a deep keeled yacht in a blow and see which one gets blown downwind quickest. The RIB will also be turned beam on to the waves much quicker. The deep keel is an advantage with a sea anchor. A RIB moves about a lot more, and needs a different technique (often as simple as a shorter line to the sea anchor than with a yacht, but needs to be practised for each boat).

I'm not knocking the windsock type - they can be effective, just less so than a parachute. Whatever you use, the key is to get it out and try it before the time comes when you need it. As I say, I use mine quite a lot: sometimes if I have divers in the water, sometimes if it's uncomfortable to lie beam on when I'm debriefing students after an exercise at sea.

Pablo · 04 February 2008, 13:06

I use the windsock type floating anchor all the time. Whilst spearfishing I tend to do drifts over the most interesting spots. So long as the wind and the tide are not moving in the same direction its very handy at slowing the boat down so i'm not swimming after it all the time.

codprawn · 04 February 2008, 17:39

Quote:

Originally Posted by SeaSkills

Try parking a RIB next to a deep keeled yacht in a blow and see which one gets blown downwind quickest. The RIB will also be turned beam on to the waves much quicker. The deep keel is an advantage with a sea anchor. A RIB moves about a lot more, and needs a different technique (often as simple as a shorter line to the sea anchor than with a yacht, but needs to be practised for each boat).

I'm not knocking the windsock type - they can be effective, just less so than a parachute. Whatever you use, the key is to get it out and try it before the time comes when you need it. As I say, I use mine quite a lot: sometimes if I have divers in the water, sometimes if it's uncomfortable to lie beam on when I'm debriefing students after an exercise at sea.

I know a RIB will move around more as there is nothing much under the water to stop it but watching sailing boats in my local harbour heeled over to 20 degrees or more with just the wind on the bare poles was scary. Then again with in mast furling etc have you seen the surface area of most masts these days??? it doesn't take much wind to move a RIB but it also doesn't take much to stop it either!!!

jwalker · 04 February 2008, 17:50

Just a wee word in yer ear; if you've got a sea anchor stored for a good length of time, check it, not when you need it in anger, cos if it's been damp the stitching may have rotted.
Don't ask me how I know.

codprawn · 04 February 2008, 18:06

Quote:

Originally Posted by jwalker

Just a wee word in yer ear; if you've got a sea anchor stored for a good length of time, check it, not when you need it in anger, cos if it's been damp the stitching may have rotted.
Don't ask me how I know.

Thats mine buggered then!!!

alystra · 04 February 2008, 18:15

Quote:

Originally Posted by codprawn

I know a RIB will move around more as there is nothing much under the water to stop it but watching sailing boats in my local harbour heeled over to 20 degrees or more with just the wind on the bare poles was scary. Then again with in mast furling etc have you seen the surface area of most masts these days??? it doesn't take much wind to move a RIB but it also doesn't take much to stop it either!!!

Yes, the problem is inertia. Boats at anchor tend to 'sail' on a figure of eight course either side of the anchor - 'ranging' I think it's called. The maximum pull on the cable is when the bow reaches the end of the scope and is pulled round to bring the wind on the other side. That's when, if it's going to, the anchor will drag.

If it holds, the inertia of the boat makes it move upwind as it turns, the cable goes slack, and with the boat at an angle to the wind, it starts to 'sail' across and down the wind until the cable tightens again and the bow is pulled round. My 40ft heavy long keeled ketch used to get up to 2knts. while doing this in F8-11. The heavy chain (60 metres in 6 metre depth - well, 30 fathoms in 3 fathoms depth, it was that kind of boat) could be pulled almost horizontal, with two boat lengths visible above the surface.

Ribs don't have anything like the inertia of a keel boat, or the windage, and I've been surprised at how well chain and rope holds with a scope of just three times the depth. If there's enough room and if in doubt though, chuck it all out. Anchor cable is no use to you if it's in the locker.

codprawn · 04 February 2008, 18:19

Yup that's exactly what I meant.

alystra · 04 February 2008, 18:23

Never use ten words if a hundred will do.