Sea anchor question

[sonofasailorsailing]

OK, here's a stupid one. We bought our boat last year and are just now finding new and exciting things out about her. Last night, while below in the aft storage area, my wife discovered a large plastic bag sitting on top of a tire, a 4.8" x 12" tire to be exact, mounted on a rim. Upon further investigation, I discovered the bag contained a sea anchor with deploying line. Now this makes sense to me, but what on earth is the tire for? I wanted to throw it away but my wife said, "No, it has to be here for a reason." Our boat, by the way is 33' long and weighs 9 tons, so this obviously does not go on a trailer. Any ideas?

 

[Gary Wyngarden]

A Drogue

Some people will use a tire as a drogue to slow the boat down if you are surfing down the face of following waves. This may help to keep the bow from plunging into the water at the bottom of the waves and may help to keep from pitchpoling. Reports are mixed on the effectiveness of a tire. If you are really concerned about this issue, a purpose made drogue will probably be more effective. Hope this helps.Gary WyngardenS/V Wanderlust H37.5

 

[Bill O'Donovan]

Sea anchors

Are found in some catalogues, notably those dealing with offshore gear. Few people venture far out enough to get caught in a huge storm, but you never know. Might be worth asking the broker if the previous owner ever deployed yours.

 

[David W]

I wonder what kind of sea anchor it is?

I haven't seen commercial ones that require a tire to be used.I have heard of just trailing a tire on a warp when running before a storm but it does not seem to be effective as the tire tends to skip across the surface.I found the book "Storm Tactics" presented good discussion on sea anchors.

 

[Franklin]

Why drag?

Why would one need to create drag? Couldn't you just use less sail (reefing)?

 

[Fred Ficarra]

Franklin, you can't have sails up in a serious

storm. And being blown downwind, with the waves can mean excessive speed, even under bare poles. Warps, (long ropes deployed overboard) or something like that tire are used to maintain control when running. A sea-anchor is the opposite. It's used as if you are hanging onto the edge of a cliff by your finger tips. All these methods are deployed depending on your boat, the crews' condition and the wind power. As far as discussing 'seamanship', this is IT.

 

[Gary Wyngarden]

Drag

When the going gets really tough, there have been reports of folks "sailing" downwind under bare poles and being pushed by the waves at a rate that could drive the bow under in the trough and create a tendency to pitchpole.In these situations, you can use long warps on their own or with tires or anything else to create drag to slow the boat down and reduce the risk of pitchpoling. But a good purpose made drogue works the best.Gary WyngardenS/V Wanderlust H37.5

 

[J.B. Dyer]

Broaching

Hi Franklin:It also helps to keep from broaching in a storm. I've never heard of the "tire" method, drogues and sea anchors yes, but not a tire! I guess anything would help though, better than nothing.

 

[Gary Wyngarden]

Diasagree on Broaching

I could be wrong about this, but I don't agree that a drogue helps to prevent broaching. It seems to me that the more boat speed you have with water going past your rudder, the more effective it will be to make course corrections to keep from being beam to the waves.Gary WyngardenS/V Wanderlust H37.5

 

[Rob]

Like a Parachute

Well a sea anchor works like a parachutte - maybe the chute (anchor) runs through the tire and the tire then pulls back or moves forward depending on speed and drag to let the chute open (as velocity increases the tire moves back) or close-up (as velocity slows). Envision what an open parachute looks like. Used in extremely heavy winds/waves.I am not an expert here - only read books about Sea Anchors but that's how I imagine a tire could possible fit-in.Rob

 

[Fred Ficarra]

Rob

I'm assuming here. The drogue (chute) is set from the bow. It keeps the bow pointed into the wind, of course, and is used when the crew deems it to be the best method to maintain control. The tire is set from the stern to slow the boat while running under bare poles to maintain course. If running too fast or too slow(?) the boat is prevented from spinning out and going beam-to. (broaching)But this boat weighs 50% more than my H34 and is a foot shorter so that's a different 'horse' out there.

 

[Arlyn Stewart]

quartering sea

Gary, regardless of getting the boat going fast enough for flow past the rudder... a following or quartering sea does some interesting things. One is that the following sea momentarily stalls the rudder as the sea flows under and cancels the water flow over it. With no rudder lift, the other forces on the hull and sail plan have their way momentarily.More often a quartering course is selected over a dead downwind, when the sea flows under, it also impacts the rudder and keel surfaces at the same moment as the stall. The effect is to yaw the boat and if the yaw force gains momentum, a broach is possible. The potential is greatly reduced by good helmsmanship which vanes the rudder to the quartering sea at the moment it flows under and then quickly returning it to course.The helm timing can be critical to avoid a broach but can be reduced by a warp which opposes the yaw forces.

 

[tomfoolery]

Drogues are different from sea anchors

Good point Arlyn.Drogues are deployed off the stern and are used to keep the vessel from exceeding its hull speed and becoming unmanagable and to assist in keeping the stern towards the breaking seas when you are heading (usually downwind) with the direction of the seas. You obviously continue to steer the vessel, either under bare poles or storm canvas, down wind - if you have room down wind to do that.Parachute and other sea anchors are deployed off the bow and are used to hold the vessels bow facing the breaking seas. The vessel is for all intents "stopped" (although it will be drifting with the current) this is akin to being hove to, but in excessive waves and wind you cannot just back the jib and heave to so you deploy a storm anchor off the bow, lower all sail go below and close up the boat and hope for the best (other than checking the pendant at the bow for chafe).The Tire would be used as a drouge, at the end of a line deployed of the stern. It slows the boat and keeps its stern towards the waves. It would not be used with the parachute sea anchor

 

[David W]

What would the tire be if

it were deployed off the bow? Drogue? Sea anchor? Or forward deployed tire?Not to be contrary but if a sea anchor or drogue is deployed from the stern is that not serving the same purpose as a warp, tire or any other object deployed from the stern?All create drag, all will either slow the boat down or "anchor" it. The degree to which they slow the boat down would depend how big, amount of drag created etc.Frankly if I were in a situation that I need to heave to, I would drag whatever I had from the bow, and lead a line back to the stern to drift at an angle other than than perpendicular to the wave sets. If I had a tire I would use it. If I had a sea anchor I would use that. I would use whatever I had and worry about what it is called later.

 

[J.B. Dyer]

Arlyn

Well said!

 

[Malcolm Young]

David - I wouldn't use just a tire off the bow

If you deploy something off the bow you want it to strongly resist drift ie you want a sea anchor not a tire or drogue. The reason for this is if a large and steep wave hits you a little to one side of your bow it will push the bow strongly to one side with a tire (or drogue) as the tire does not have much grip on the water. This would lead to being thrown across the wave and a possible broach. On the other hand a sea anchor will hold the bow into the wave as it is bigger and has much more drag. The place for warps, drogue or tire? is off the stern as they still allow you to go fast enough to steer. However, I would think a sea anchor off the stern is more likely to lead to getting pooped (wave over the stern into the cockpit)By the way - my understanding is that with a sea anchor off the bow it is best to deploy the sea anchor on a bridle which angles the bow slightly into the waves to keep the boat from slewing back and forth from one side to the other.This is based on reading various books plus some logic - fortunately I have not had to deploy either - maybe there is someone out there with experience.

 

[Fred Ficarra]

Maybe Malcolm but not likely.

It's the stuff we read about in adventure stories.Arlyn, do you write textbooks for a living?

 

[Don12364]

Rubber Snubber?

Could it be used as a snubber to relieve the snatch loads generated when the boat pitches. i.e. make the rode fast to one side then bring the rode across the tyre with slack and make another knot before taking the end to a cleat on board. Or -it might fit neatly over the bow roller to prevent the inevitable chafe on sea anchor rodes. I know a guy who lost two sea anchors in the same storm off the US west Coast. Nobody would go on the foredeck to freshen the nip on the cleat and they didn't use chain over the roller.Or - why not ask the PO it might have been for his bike!

 

[Gary Wyngarden]

Good point, Arlyn

I leave for a few hours to go work on the boat and all hell breaks loose. I buy Arlyn's point as I really hadn't thought about the stalling effect of the following waves.We quartered down some 12 footers last summer but didn't have any trouble and didn't even consder any kind of drag.Even though I understand Arlyn's point, I still don't like stuff in the water behind me. There's always the wave that comes from other than the prevailing direction and I don't think I want anything holding me back from turning to handle it from the proper angle.May this entire discussion be theoretical for all of us.Gary WyngardenS/V Wanderlust H37.5

 

[TT]

Check the initial post

The responses to this have been very informative , but the initial post questioned the utility of a 4.8 x 12" tire, MOUNTED ON A RIM, assuming it may be part of the sea anchor or drogue found in the lazarette.This is a wheelbarrow sized tire, or one found on the smallest of utility trailers. An unmounted tire from a full sized car or light truck could be used as a drogue, but who in their right mind would try to use a dinky little tire mounted on a rim for that purpose ??? To Gary W's final comment "may this entire discussion be theoretical....." I would like to add, AMEN.