Parachute Sea Anchor Size ?

[mattyc]

Just wondering, is there anything that speaks against having an oversized parachute sea anchor other than the increased size/weight of the gear and increased handling difficulties. I'm looking at a used one at the moment, good shape etc., but it is 1 size larger than recommended, 15' diameter instead of 12' diameter. Can a parachute sea anchor be too big and cause problems?

[Hyprdrv]

I have no idea of the size boat you have.
I happen to be reading the Pardey's 3rd addition of Sea Tactics. Page 82 referring to the Tasman Sea, what the claim was their worst storm. Under Lessons Learned they state "Having to large a Para Anchor can be a mistake". (8' on a 24' boat). "A 12' held twice the volume of water..". They go on to say they felt that most manufactures lead sailors to err on the side of too large a size.

For what it's worth,
Steve in Solomons MD

[Kettlewell]

The short answer is no. The function of the parachute sea anchor is to act like an "anchor." You don't want to move back, or at least very little, so the bigger the better as long as you can handle it. The length of the road to the anchor will determine the quality of your ride--in other words, the stretch in the road will cushion the blows, not any movement of the chute backwards. I wouldn't be at all concerned about going one size bigger.

The Pardeys have their own rather unusual set up that is really heaving-to aided by a small parachute. They believe in drifting back to create a slick to windward, which helps prevent breaking wave strikes. I can't argue that their system doesn't work for them, but it is not the norm.

[PamlicoTraveler]

People use sails when they don't have a parachute, so no. Anything big enough to do the job would be good.

[capngeo]

Has anyone here ever used an old Mil-Surplus aerial parachute? I wonder if they would be strong enough?

[PamlicoTraveler]

Originally Posted by capngeo

Has anyone here ever used an old Mil-Surplus aerial parachute? I wonder if they would be strong enough?

I think that's what the Pardey's used but I'm not sure.

[apneseth]

Being the project manager for the ShipArrestor project (see Stopping a drifting tanker, preventing disaster | Shiparrestor) I have done several test with sea anchors that were both smaller and bigger than the norm. Admittedly this was done to investigate the effects on commercial ships but as the ships we tested varied from a submarine to an anchor handler to a LNG tanker I should think the same would apply to a yacht.

If you use a sea anchor that is too big it may not inflate completely. This should not be an issue.

If you use a sea anchor that is too small you will obviously drift backwards faster which should not matter much. In addition though the forces may be larger than the cloth can withstand and the sea anchor might get pulled down, causing all kinds of trouble.

I must agree with Kettlewell when it comes to the Pardey's style of using the sea anchor. If it works for them fine but the loads will positively be higher and the roll motions would be more pronounced.

[Kettlewell]

Yes, people have used various surplus parachutes as sea anchors. However, the current commercial versions are already set up for boating use with things like appropriate swivels, launching containers, attachment points for a float, etc. I'm sure you could get a surplus chute to work, but you'd have to do some study and work to duplicate the effectiveness of the boating-specific ones. You have to really think about launching the thing--picture yourself on deck, at night, in a gale, trying to launch a pile of light nylon and strings into the sea without getting tangled in the whole mess. The boating companies have worked out how to do it safely.