Drag Cost for Trailing a Line Astern

[Little John]

Harness and tethered is the road to go. Think of knocked out by your boom. How can you help yourself? It is like safety belt in the car. Meantime we are used to it and it saved a lot of lifes. Never going over board is the only safe way to go.

[zstine]

I agree that Calculating drag is far to complex with surface effects like making wake and splashing adding to the drag analysis. In practicality, the effect of drag on boat speed is less as wind increases. If you are doing hull speed, the drag on the boat is hundreds or over a thousand pounds. Adding a rope drag of 20lbs will be negligible. however, if sailing at 2 - 3 knots, the rope may slow you down by maybe 0.1 -0.2 knots, which is a significant % of speed.


As far as the MOB issue, The rope led to turn the engine key off and disable the auto pilot is an effective way of stopping the boat... during the day anyway. At night it would be hard to find the rope. if you have crew, an AIS or bluetooth(much cheaper) MOB alarm is good way to alert them and get found. The best option is to just not go overboard in the first place. We almost always had more than 1 person on deck during the day, so the risk is much less than at night. During night watch, we stayed in the cockpit. If it was calm, we would harness in to go forward without waking the crew, but if it was blowing, we would wake an other crew member before going forward.

[MicHughV]

I once went thru' a very bad storm and had to slow the boat down...and tried streaming a long line (200' anchor line, 5/8" nylon), but it didn't make the slightest difference..for one thing, only about half the line is in the water, the rest is in the air...
then I tried two lines tying the ends together, and as before, it made little impact to boat speed......
dragging a line for any period of time will incur a variety of growth...

as above....remain tethered to the boat is the smart choice here..

polypropylene line floats, but is also very slippery to hold...but regardless, a fully clothed person would not be able to hold onto a line for very long.....the drag of a person would enormous.....

[SteveSadler]

We have trailed a line on passages many times for fun. Jump off the bow, swim like hell to the line, catch it 50' behind if you're fast and have practiced it a few times, and hand over hand to the transom. From this point, climbing aboard requires super human strength, or a ladder that you can pull out one handed, long enough to get a foot on a rung. of course we wore swim suits occasionally, with real clothes on, drag multiplies quickly and reduces chances of success. Line needs to be 3/4" as it's really hard to grip a 1/2"line without slipping. Knots help, but only to hold on, not get back. I do use 100' line for that purpose when I single hand only because I'm well practiced,
I doubt any of my crew over 50 could get it without practice and good swimming skills.

[SailRN]

https://www.pbo.co.uk/seamanship/is-...KdDSjwdzL3s.01


Tie a Midshipman's Hitch (can be tied under load) after grabbing the line, before you're exhausted. Theoretically, you could use the advantage of this knot to work your way back to the boat when the loop is around you and you use the knot similar to a Prussik. And at the last metre or so at the boat end the line could have loops such as the Alpine Butterfly knot where you could use both your feet and hands to climb back aboard.


Overboard: The Midshipman’s Hitch Knot is promoted by Ashley (ABOK # 1993, p 325) as the only knot to tie in the following unlikely but critical circumstance: you fall overboard and catch hold of the line which you have prudently left trailing astern and find yourself hanging on with difficulty. Before you tire, you manage to bring the bitter end of the rope around your back. You then have to tie a suitable knot to make a loop around you. A bowline cannot be tied under load. Two Half Hitches will slide and constrict you. The Rolling Hitch is the answer. Even as the second turn is tucked “up” into the correct place, the major strain is taken and the final Half Hitch can be tied with less urgency.


If you don't want to trail a larger line, consider perhaps trailing a small diameter line in the water, but tied to a larger line aboard which is deployed when hanging on the small line. The larger line could have loops (Alpine Butterfly Knot) tied at convenient spacing to aid "climbing" back to the boat, and then climbing aboard. Loops where you can use your feet are advantageous to fighting the current against you and climbing back aboard.

[Seman]

Originally Posted by BenBowSirocco

Everyone,



Thank you for the great responses already. I guess I do need to explain my hair-brained plan.



We are planning a Pacific crossing for next spring and my partners biggest fear is coming on deck with someone missing. So we are exploring some ideas beyond the "harness at all times" thought process- which I find inhibitive. Obviously its a personal choice and harnesses have their place when the weather is ominous.



The intention of dragging 300' of polypropylene line behind the boat is for overboard retrieval, but perhaps not as you imagine because I agree with you, the drag induced by your body is significant and its unlikely you would be able to drag yourself up any appreciable distance- even under a high adrenaline circumstance as falling overboard.



I have for fun- under a planned circumstance- jumped from the spreaders, grabbed a trialing line dragged behind and climbed along the line back into the boat at 3 or 4 knots boat speed and its aided by, a swim suit, a head down swimming posture and keeping your arms and grip close into your body- like swimming. But this is impractical in any real world circumstance- especially if wearing clothes and a bunch of other reasons.



It does seem to me it should be possible to use a specifically weight rated fishing line as a gasket to the 300' of poly so when you get a "fish on" i.e. a fallen crew member grabs the trailing line and the fishing line breaks- this would then activate a bungee cord and disable the windvane, causing the boat to round up and hopefully alerting other crew, as well as allowing the fallen a chance to pull themselves closer.



Will this work? Is this silly?

Obviously it needs testing on the water. But I thought I would start by trying to find some number to work with from people smarter and more experienced than myself.
This is also why I was wondering the drag in pounds between 5/8 or 1/4".



The fishing reel comparison was a great point. Even a non-fisherman like me knows that 15lbs of drag holds back some big lures.


My thought was a foot size loop at the end of the line, no knots along it.

When I was single handing I dragged a floating sky rope behind the boat with a large coke bottle attached to the end. The + autopilot wire I cut and re-connected with a spade connector. This connector was tied to the floating line with a small diameter rope. Any pull on the sky rope would disconnect the auto pilot and the boat would stall. Another small rope connected to the throttle/gear would stop the boat when motoring.

[BenBowSirocco]

Originally Posted by SailRN

https://www.pbo.co.uk/seamanship/is-...KdDSjwdzL3s.01


Tie a Midshipman's Hitch (can be tied under load) after grabbing the line, before you're exhausted.


Overboard: The Midshipman’s Hitch Knot is promoted by Ashley (ABOK # 1993, p 325) as the only knot to tie in the following unlikely but critical circumstance: you fall overboard and catch hold of the line which you have prudently left trailing astern and find yourself hanging on with difficulty. Before you tire, you manage to bring the bitter end of the rope around your back. You then have to tie a suitable knot to make a loop around you. A bowline cannot be tied under load. Two Half Hitches will slide and constrict you. The Rolling Hitch is the answer. Even as the second turn is tucked “up” into the correct place, the major strain is taken and the final Half Hitch can be tied with less urgency.

A truckers hitch to hold your foot in would be faster and easier than bringing the end of the line up to you holding with only one hand. Bearing your weight with a stiff leg would buy a lot of time.




No one on the boat will be over 34 years since I’m the oldest. We are all active and strong people. The sugar scoop on our boat (Ovni 37) is practically wet and when at speed is very easy to reach and the windvane is going to be there as the ladder.

But like I stated previously- I’m not advocating the climb the line into the boat trick. The idea is to break the gasket and cause the boat to round up awakening the crew.

Harnesses have their place and are an important piece of gear. But it’s a personal choice and I am not going to wear one unless I feel conditions demand it. I know that falling overboard means I’m likely a dead man and treat the situation with the level of respect that it demands of me.

I do like the idea of Bluetooth overboard devices- a bracelet seems simple- assuming they are rechargeable.

Great idea everyone! Appreciate it.

Seems to me the spool of 5/8 would be the best answer. It will be a great morning line. Easily reeled in when the wind is light. Something you can grab.

Not let’s just pay attention to what we are doing and hopefully we never use it. Haha

[Cheechako]

Drag a boogie board instead?

[BenBowSirocco]

Originally Posted by Cheechako

Drag a boogie board instead?

Haha!

How many do you think would get snatched and lost??

[SailRN]

Originally Posted by BenBowSirocco

A truckers hitch to hold your foot in would be faster and easier than bringing the end of the line up to you holding with only one hand. Bearing your weight with a stiff leg would buy a lot of time.

Hmmmm, I've never tried tying a Trucker's Hitch under load, with a single hand... Think I'd use the Midshipman's knot that I've tied under load with a single hand, and as recommended by a circumnavigator (Animated Knots).




And that Midshipman's Hitch works a lot like a Prussik and can be used to work yourself to the boat, and yes, you can put your foot in it.

[MicHughV]

theory is all good well....

but what do you do at night....in the rain.....with seas running...breaking crests....etc....

do yourself a favor and clip on...I had flat nylon webbing run down both sides of the cabin....tensioned pretty tight...to which I could clip a harness with a short leash...

[philiosophy]

I think it is a very bad idea to trail a long line over the stern. Especially at night. When fast moving storm fronts come on the boat,sometimes the wind dies and swings around in the opposite direction leaving you with the need to get the sails down and engine started and engaged to regain steerage way. This happened twice on my boat in Feb on a trip down the East coast of Australia with very experienced crew. What do you think might happen in this case to a 100 meters of small line with 2 propellers.

I believe there are way too many movies, books, and stories sensationalizing this scenario. Then there is.just plain fear from inexperience. Good safe practical policies and time at sea will probably alleviate that biggest fear.

1. Don't leave the cockpit/Helm area at night without getting another person up, and clip on. Depending on the size and type of Cat this might be even more important.
2.There are personal AIS Transponders to wear on your life vest. Make sure there is a water activated strobe light on the vest. A person in the water especially in any sea conditions at all is very hard to spot even with the aforementioned gear.
Personally I tell all new crew..." if you fall over the side, your a gonner". All practice should be to not fall overboard.
3. See number's 1. And 2. Reduce sail as the light goes out of the sky. Don't forget to tell your partner stories about the amazing stars,sattelights, planets, and constellations they will see on balmy nights when the warm breeze caresses her skin and there is no one there to tell her its not ok.

[boat driver]

Originally Posted by BenBowSirocco

Interested in hearing some thoughts and opinions on the amount of drag induced by trailing a long line astern.



The discussion of trailing an "Overboard Line" is already in other threads.



I am looking for information on the amount of drag it would induce to a sailboat to drag 300' (92m) of polypropylene line astern.

The big question being, how much will it negatively effect sailing speeds?



This community is so full of smart people I am looking forward to some ideas on how to calculate the drag in pounds.



Part of my goal is to better understand what size line I might purchase for this purpose. Should it just be a spool attached to the arch of 5/8"- 16mm, with the multipurpose use of tying ashore, or should it be a light/thin line dedicated for the purpose say 5/16" or dare say 1/4".

what is the purpose?
fishing, storm warps, Man-overboard?

[MJH]

Originally Posted by BenBowSirocco

Interested in hearing some thoughts and opinions on the amount of drag induced by trailing a long line astern.

The discussion of trailing an "Overboard Line" is already in other threads.

I am looking for information on the amount of drag it would induce to a sailboat to drag 300' (92m) of polypropylene line astern.

The big question being, how much will it negatively effect sailing speeds?

This community is so full of smart people I am looking forward to some ideas on how to calculate the drag in pounds.

Part of my goal is to better understand what size line I might purchase for this purpose. Should it just be a spool attached to the arch of 5/8"- 16mm, with the multipurpose use of tying ashore, or should it be a light/thin line dedicated for the purpose say 5/16" or dare say 1/4".

One of the first rules of sailing is to stay on the boat. Concentrate on everything to keep crewmembers on board including harness and teather properly connected to the cockpit floor or jackline on deck plus pocedures you both develop together and adhere to 100%

Good luck.

~ ~ _/) ~ ~ MJH

[rickpyne]

If you want to know how much drag is caused by a trailing line, while dragging line attach boat end of line to a set of fish scales and get the reading in pounds or kilograms. 300ft might need a big set of scales...