Portal
Forums
Visit our Popular Forums
The Fleet
Monohull Sailboats
Multihull Sailboats
Powered Boats
General Sailing
Antares Yachts
Fountaine Pajot
Lagoon Catamarans
Cruising Business
Boat Classifieds
General Classifieds
Crew Positions
Commercial Posts
Vendor Spotlight
Life Aboard a Boat
Provisioning: Food & Drink
Families, Kids, & Pets Afloat
Recreation, Entertainment, & Fun
Boat Ownership & Making a Living
Liveaboard's Forum
Seamanship, Navigation & Boat Handling
Seamanship & Boat Handling
Navigation
OpenCPN
Training, Licensing, & Certification
Health, Safety, & Related Gear
Rules of the Road, Regulations, & Red Tape
Engineering & Systems
Const. / Maint. / Refit
Product / Service Reviews
Electronics: Comms / AV
Electrical: Batts / Gen / Solar
Lithium Power Systems
Engines & Propulsion
Propellers & Drive Systems
Plumbing / Fixtures
Deck Hdw: Rigging / Sails
Aux. Equipment & Dinghy
Anchoring & Mooring
Join Now
Photos
Photo Categories
Member Galleries
Life Onboard
Sailing in the Wind
Monohull Sailboats
Multihull Sailboats
Power Boats
Cruising Destinations
Equipment
Maint. & Boat Building
Marine Life
Scuba Diving & Divers
General Photos
Recent Photos
Upload a Photo
Classifieds
Listing Categories
Boat Classifieds
Crew Positions
General Classifieds
Add General Classified Listing
Add Boat Listing
Add Crew Listing
Builders
Beneteau
Catalina
Hunter
Jeanneau
Searunner
Fountaine Pajot
Lagoon
Antares
Morgan
African Cats
view more »
Crews
Crew Wanted
Crew Available
Library
Rules
Wiki
More
Enhance Your Account
Calendar
Links
Meet the Mods
Meet the Advisors
Signup for The Daily Cruiser Email
Cruisers & Sailing Forums
>
The Fleet
>
General Sailing Forum
Drag Cost for Trailing a Line Astern
Click Here to Login
Register
Vendors
Sponsoring Vendors
Vendor Deals & Promos
Display List of Vendors
Display Vendors by Location
Display Vendors by Map
Register your Company
FAQ
Community
Calendar
Today's Posts
Search
Log in
Community Links
Social Groups
Pictures & Albums
Members List
Meet the Mods
Meet the Advisors
Signup for The Daily Cruiser Email
Search Forums
Show Threads
Show Posts
Tag Search
Advanced Search
Google Custom Search
Search Links
Advanced Search
Search Gallery
Advanced Search
Go to Page...
Page 3 of 4
<
1
2
3
4
>
This discussion is proudly sponsored by:
Please support our sponsors and let them know you heard about their products on Cruisers Forums.
Advertise Here
Thread Tools
Search this Thread
Rate Thread
Display Modes
28-08-2021, 17:55
#
31
goboatingnow
Nearly an old salt
Join Date: Jun 2009
Location: Lefkas Marina ,Greece
Boat: Bavaria 36
Posts: 22,801
Images:
3
Re: Drag Cost for Trailing a Line Astern
I know for a fact anything over 2 knots , and I can’t hold on , never mind hauling myself along the line. If you have heavy
weather
gear
or boots , there’s zero hope, zero. Above 2 knots you get dragged under anyway and you can’t clear your airways
When I brief my crew , I say “ heres my
mob
routine “ , I turn and wave bye bye to the stern . Do everything in your
power
not to fall off the
boat
, causes the chances of surviving are slim
As for drag , can’t say , but we streamed 300 feet of warp in a U behind the
boat
in a big storm , it was bar tight in the
water
and needed a
winch
to retrieve it.
__________________
Interested in smart boat technology, networking and all things tech
28-08-2021, 18:07
#
32
ChrisJHC
Registered User
Join Date: Aug 2020
Location: Melbourne, Australia
Boat: Swarbrick S-80
Posts: 953
Re: Drag Cost for Trailing a Line Astern
Like most people, I’d recommend PFDs and harnesses tethered on after dark.
They’re really not that bad once you get used to them.
AIS
MOBs are also good and will set off the
alarm
on your
VHF
to wake up the crew.
Other options (that I don’t recommend):
Harness only (no PFD) and tethers. Attach the
AIS
MOB
to the harness.
Put the AIS MOB in a “bum bag” (I think they’re called fanny packs in the US) and just wear that. You can then hand the bum bag over to the oncoming crew
member
when you change over. Won’t stop you falling
overboard
but will let the crew know that you’ve gone.
28-08-2021, 19:20
#
33
Dooglas
Registered User
Join Date: Sep 2010
Location: Oregon City, OR
Boat: 37 Uniflite Coastal Cruiser
Posts: 805
Re: Drag Cost for Trailing a Line Astern
Quote:
Originally Posted by
BenBowSirocco
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.
Yes, it is a personal choice for you and your partner. If
safety
for two people (the second of whom probably couldn't
single
hand the boat on a
remote
passage) is the important consideration, then you need to get beyond this harnesses are inhibiting point of view. A harness with
PFD
is how you do this. You aren't going to grab a line as it streams by you and pull yourself back to the boat in the event of an MOB. And if you just want to tell your partner that is the plan so you won't have to hear about this anymore - shame on you.
28-08-2021, 19:52
#
34
thinwater
Writing Full-Time Since 2014
Join Date: Nov 2008
Location: Deale, MD
Boat: PDQ Altair, 32/34
Posts: 9,906
Re: Drag Cost for Trailing a Line Astern
Just for fun, I decide to test the theory that a floating line could trip a
sea anchor
stopping the boat. Bottom line?
It worked on my 2000-pound boat at speeds up to 12 knots and could be easily engineered to
boats
up to ~ 20,000 pounds at 7-8 knots using different materials. Heavier than that is quite possible but I did not investigate it.
That line streams by faster than you think. You will notice I'm about 140' behind the boat (about 6 knots in the video--some tests were twice this speed) by the time I get to the line. Yes, I jump off an outrigger and I don't really rush, but likewise, it is planned and daylight. You should allow 250 feet of line.
Even with the boat slowed to 2 knots, it's a bit of
work
to hand-over-hand that distance. And I go rock climbing every week. Not terribly hard, but allowing for weather and heavier clothes, hard enough.
As I said, this was just a fun summer
experiment
that has possibilities if someone wanted to take it on. The line is very low drag (few pounds) because it has no knots and only a small float (you really do want a float, for visibility and grasp) and loop at the end.
Sail Delmarva: I Just Want the Boat to STOP!!
__________________
Gear Testing--Engineering--Sailing
https://sail-delmarva.blogspot.com/
28-08-2021, 21:20
#
35
SailRN
Registered User
Join Date: Feb 2015
Location: South Carolina
Boat: SeaRunner 37, 11.3 metres
Posts: 445
Re: Drag Cost for Trailing a Line Astern
Quote:
Originally Posted by
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...
That sounds familiar.
__________________
In theory, practice and theory are the same. In practice they are not.
29-08-2021, 09:43
#
36
rmlarson1098
Registered User
Join Date: Sep 2016
Boat: Montgomery 23
Posts: 220
Re: Drag Cost for Trailing a Line Astern
Quote:
Originally Posted by
BillKny
There are too many variables to actually calculate it. Diameter of line? Boat speed? surface roughness of the line being used?
And then once you have it "in pounds" what does that tell you?
Taking my
engineer
hat off, and just a touch of practical experience the amount of drag from a trolled line is: Trivial.
How do I know? Because I have pulled in lines that were dragging behind a boat, and you can easily hole them in one hand. Certainly the total pull is less than 10 pounds. I troll
fishing
lures than pull way harder than 100 feet of 1/2" line, and the drag on the
fishing
reel is set at 15 pounds. So there is an upper limit for you.
If you are asking because you want to climb back onboard after you have fallen off, just FORGET IT. You can not. You do not have the strength to pull yourself back to the boat if it is moving at anything more than a dead drift. Try it and see.
Well said. Certainly 300 feet of 'overboard line' is ridiculous. 30' would be a tough climb...unless you're a gymnast.
We dragged 100' of 3/8" floating line that was supposed to disconnect the
wind vane
. Even for that purpose it's slippery, and you'd better have some knots in it. Towing warps are something else entirely of course.
29-08-2021, 10:12
#
37
thinwater
Writing Full-Time Since 2014
Join Date: Nov 2008
Location: Deale, MD
Boat: PDQ Altair, 32/34
Posts: 9,906
Re: Drag Cost for Trailing a Line Astern
Length is more than some of you think.
Boat will be going 7-8 knots if it windy enough to fall off.
. At least, we should assume so. 13.5 ft/s at 8 knots.
The fall will be a surprise and will most likely be from the extreme beam. figure 3-4 seconds to orient yourself, 3 seconds to swim to the line, and 2 seconds to grasp and get a good grip. That's nearly 10 seconds, or 140 feet, assuming no disorientation or injury, and that it is daylight.
It took me 8 seconds in my video, and it was daylight and I dove in. The boat was pretty far away. I had 150 feet of line out and barely got to it.
Really, 200 feet is the bare minimum. 300 feet is sensible. That's only 20 seconds to surface, get your wits about you and find the line (not obvious in the dark). 30 feet is stupid short--you won't even have surfaced yet.
Streaming a warp in a U is compeletly different and the drag is far, far higher. But easy to recover once you release one end, which is an advantage. BTW, trailing a warp only works if you weight the center with chain to get it to sink.
That's just the math.
__________________
Gear Testing--Engineering--Sailing
https://sail-delmarva.blogspot.com/
30-08-2021, 10:38
#
38
Moontide
Registered User
Join Date: Feb 2006
Location: Eastern Caribbean for the 2020 season then east coast or Panama
Boat: Lagoon 470 cat
Posts: 700
Re: Drag Cost for Trailing a Line Astern
Have not read all the other responses so this could be redundant.
I bought a personal AIS MOB device. If anyone goes over when on watch alone (and has it on them) the unit will activate the AIS
alarm
on the
VHF
radio
. It is loud enough to wake anyone down below sleeping.
I like this over the personal PLB since
rescue
by a nearby boat is much quicker, and surer, than waiting for the
EPIRB
responders to find you.
I've dragged behind a boat while underway and, from my experience holding on for an extended period at anything over 2-3 knots is probably not going to happen.
01-09-2021, 21:13
#
39
KP44
Registered User
Join Date: Jan 2017
Location: Sea of Cortez
Boat: Kelley-Peterson 46 cutter
Posts: 890
Re: Drag Cost for Trailing a Line Astern
Quote:
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".
If you're only dragging this in heavy weather, your boat has plenty of
wind
power
.
If you drag this most of the time, it might slow you by half a
knot
or less in light winds. If this gives you peace of mind, it is well-worth the reduction in speed.
Kon Tiki (raft that crossed the Pacific) dragged its
inflatable
dingy on their longest line during heavy weather. They knew that no one could swim and catch up with the raft. A sailboat is much faster. Poly line is a good choice. A small
fender
and a loop at the bitter end might be a good idea.
01-09-2021, 21:58
#
40
KP44
Registered User
Join Date: Jan 2017
Location: Sea of Cortez
Boat: Kelley-Peterson 46 cutter
Posts: 890
Re: Drag Cost for Trailing a Line Astern
There is a blue poly line that is partially UV resistant fibers. I use it for dingy painters and can trust it for 2 years in tropical sun. Since poly does not splice fair, I use zinc-plated "rope clamps". They are metal pounded together with a hammer and they last 2 years without failing. I put a small net buoy near the end of the painter so the metal
rope
clamps will not sink.
01-09-2021, 22:34
#
41
Don C L
Moderator
Join Date: Sep 2014
Location: Channel Islands, CA
Boat: 1962 Columbia 29 MK 1 #37
Posts: 14,744
Images:
67
Re: Drag Cost for Trailing a Line Astern
Quote:
Originally Posted by
Seman
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.
Something like that is the only way I'd consider this idea. (And I wouldn't consider it. It's a false sense of
security
.) It would have to also kill the
engine
completely and pop the clutches to douse the
sails
too. A boat that rounds up and heaves-to is often still sailing... on the other tack, albeit slowly. Or depending on what
sails
are up, it may just come around and gybe.
And the whole thing would have to be fool proof to be of value.
Things like this help to drive home how valuable a good harness is.
__________________
DL
Pythagoras
1962 Columbia 29 MKI #37
03-09-2021, 07:42
#
42
robert 56
Registered User
Join Date: May 2008
Posts: 12
Re: Drag Cost for Trailing a Line Astern
Quote:
Originally Posted by
landsend
Can you really hold on to a line and drag yourself back aboard whilst traveling at approx 5 knots? Maybe the thought of the consequences would give you the extra boost in strength!
I know we have done this on night watches when there was 2 of us onboard on passages
more of a
security
blanket but certainly not easy to pull yourself anywhere at 5kts or even slower speeds
03-09-2021, 08:10
#
43
Bill_Giles
Registered User
Join Date: Apr 2015
Location: Newhaven, UK
Boat: Bavaria 36'
Posts: 355
Re: Drag Cost for Trailing a Line Astern
There are several personal alarms available should you become separated by more than a few feet. I have an AIS personal alarm which shows position relative to the boat.
My thoughts of a drag line is that it could be rigged to trip the
autopilot
so could be quite light.
Our
rule
aboard is lone on
deck
clipped on. And at night, in the rough and in
fog
too.
03-09-2021, 08:35
#
44
smacksman
Registered User
Join Date: Sep 2009
Posts: 202
Re: Drag Cost for Trailing a Line Astern
A towed
generator
cost us about a quarter
knot
. Much more drag than 300m of line.
03-09-2021, 08:48
#
45
joelhemington
Registered User
Join Date: Oct 2019
Location: San Leon, Texas
Boat: Knysna 440 once I get my new dock and the canal gets dredged
Posts: 914
Re: Drag Cost for Trailing a Line Astern
Quote:
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.
This doesn't sound like a bad plan as it would give the MOB a way to stay with the boat. Climbing back on would be difficult if the boat didn't round up due to being on auto pilot or
windvane
. You might do it on a
catamaran
but probably not a
monohull
. The rest of the crew could get you back on board (assuming you had crew). If soloing, you'd need a way to release the swim ladder from the water. I'm guessing that the real question here is how much negative effect a drag line would have on boat speed - something I'd be interested to know. If it didn't result in too much negative drag, it would be well worth doing.
Page 3 of 4
<
1
2
3
4
>
«
Alternator not charging after nearby lighting strike
|
Buy upgrades or save for next boat?
»
Thread Tools
Show Printable Version
Display Modes
Linear Mode
Switch to Hybrid Mode
Switch to Threaded Mode
Search this Thread
Advanced Search
Rate This Thread
Excellent
Good
Average
Bad
Terrible
Posting Rules
You
may not
post new threads
You
may not
post replies
You
may not
post attachments
You
may not
edit your posts
BB code
is
On
Smilies
are
On
[IMG]
code is
On
HTML code is
Off
Trackbacks
are
Off
Pingbacks
are
Off
Refbacks
are
Off
Forum Rules
Similar Threads
Thread
Thread Starter
Forum
Replies
Last Post
Is it safe to cross astern of a fast ship in open water with a 180 feet CPA
evm1024
Seamanship & Boat Handling
140
12-12-2017
15:17
RUDDER CONTROL ASTERN: WHEEL BRAKE or LOCK without LASHING Old Twin Engine Catamaran
Bobcat
Seamanship & Boat Handling
7
01-08-2017
10:03
Hurth gearbox - loss of drive in ahead but fine in astern
GrahamW
Engines and Propulsion Systems
23
27-01-2014
08:30
Access - Boarding Astern
In Training
Monohull Sailboats
21
17-07-2013
09:17
Full Ahead to Full Astern . . . Very Quickly
deltasig
Engines and Propulsion Systems
14
13-09-2010
21:40
Advertise Here
Recent Discussions
Yanmar 4JH3-TE vs Beta Marine 60
Possibility of homebuilt plywood...
Victron MPPTs unrepairable now and...
C&N managed yacht sinks off Sicily,...
Sea Hawk bottom paints
Forced air diesel heater ducting...
Clogged holding tank
Anchoring 32' Sloop
Definition of a Noob
Rebuilt Westerbeke W80 - injectors...
Partially unwrapped front stay
Finding a root cause of torn sail
Vendor Spotlight
No Threads to Display.
All times are GMT -7. The time now is
16:02
.
-- Cruisers Forum v2.0
-- Cruisers Forum v1.0
-- Mobile
Contact Us
-
Cruisers & Sailing Forums
-
Sitemap
-
Community Rules
-
Terms of Service
-
Privacy
-
Accessibility
-
Top
Google+
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2024, vBulletin Solutions, Inc.
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2024, vBulletin Solutions, Inc.
close
Enter your Email:
Privacy Guaranteed
- your email is never shared with anyone, opt out any time.
ShowCase
vBulletin Plugins
by Drive Thru Online, Inc.