Halyard Loads? -- Never mind I found the answer.
Moderator: Jim Walsh
- bottomscraper
- Posts: 1400
- Joined: Feb 5th, '05, 11:08
- Location: Previous Owner of CD36 Mahalo #163 1990
- Contact:
Halyard Loads? -- Never mind I found the answer.
On Mahalo CD36 the main halyard runs back to the cockpit. There
is a stand up block near the base of the mast that I would like to
replace. I am trying to select a replacement block but I don't have
a clue what the loading would be. The existing block is a Hood
(no longer made) so I can't use that as a starting point.
Duh, never mind, I found it!
Found a chart on page 372 of "The Complete Rigger's Apprentice"
by Brion Toss (ISBN-13: 978-0070648401) (BTW it's a great book)
It is interesting the chart is based on the LOA of the boat only.
is a stand up block near the base of the mast that I would like to
replace. I am trying to select a replacement block but I don't have
a clue what the loading would be. The existing block is a Hood
(no longer made) so I can't use that as a starting point.
Duh, never mind, I found it!
Found a chart on page 372 of "The Complete Rigger's Apprentice"
by Brion Toss (ISBN-13: 978-0070648401) (BTW it's a great book)
It is interesting the chart is based on the LOA of the boat only.
Rich Abato
Nordic Tug 34 Tanuki
Previous Owner Of CD36 Mahalo #163
Southern Maine
http://www.sailmahalo.com
Nordic Tug 34 Tanuki
Previous Owner Of CD36 Mahalo #163
Southern Maine
http://www.sailmahalo.com
-
- Posts: 86
- Joined: Aug 7th, '09, 14:21
- Location: 1978 Cape Dory 28 #174, Sanuye, Melbourne, Florida
I'm curious
Now I'm curious.... what IS the loading?
Also, does it have reference to the loading on a 28 footer?
Also, does it have reference to the loading on a 28 footer?
There is some info here:
http://mauriprosailing.com/techinfo/Har ... rmulas.htm
http://mauriprosailing.com/techinfo/Har ... rmulas.htm
I'm disinclined to acquiesce to your request. Means no.
- Sea Hunt
- Posts: 1310
- Joined: Jan 29th, '06, 23:14
- Location: Former caretaker of 1977 Cape Dory Typhoon Weekender (Hull #1400) "S/V Tadpole"
Dave:
The chart Rich references in his post is a small line graph chart with even smaller numbers.
It looks like the "Lewmar formula" for a halyard load for an LOA 36 sailboat is approximately 2000 - 2200 lbs.
For a LOA 28 sailboat it appears to be approximately 1000 - 1200 lbs.
I do not really understand how these numbers are arrived at without knowing a lot more information than the LOA. I would think mast height, for example, would be a significant variable.
I guess maybe I should have actually studied for the math test in the GED class I never passed.
The chart Rich references in his post is a small line graph chart with even smaller numbers.
It looks like the "Lewmar formula" for a halyard load for an LOA 36 sailboat is approximately 2000 - 2200 lbs.
For a LOA 28 sailboat it appears to be approximately 1000 - 1200 lbs.
I do not really understand how these numbers are arrived at without knowing a lot more information than the LOA. I would think mast height, for example, would be a significant variable.
I guess maybe I should have actually studied for the math test in the GED class I never passed.
Fair winds,
Robert
Sea Hunt a/k/a "The Tadpole Sailor"
CDSOA #1097
Robert
Sea Hunt a/k/a "The Tadpole Sailor"
CDSOA #1097
- bottomscraper
- Posts: 1400
- Joined: Feb 5th, '05, 11:08
- Location: Previous Owner of CD36 Mahalo #163 1990
- Contact:
Halyard Loads
I guess I should have used the term graph rather than chart
in my description of what's on page 372 of the Riggers Apprentice.
It shows a plot of halyard load vs. LOA. It looks like the load for
a 28 ft boat would be less than 1500lbs, it's a small graph to
interpolate so hopefully I over estimated a little.
FWIW the title at the top of the page for the 4 different loading
graphs is "Lewmar's Formulas", I could not find anything
particularly useful on the Lewmar web pages.
Note that for a turning block like the 90 degree one on our
halyard the load on the block the load will be about 141%
of the halyard load. (see tables from previous post or this link
http://www.harken.com/charts/blockloadvangle.php)
This table shows which Harken Blocks to use vs Maximum "P" Dimension of your main sail:
http://www.harken.com/charts/BBusechart.php
I will probably be using Garhaur blocks rather than Harken since
they are more in my price range and I think they are well made
and the best value.
in my description of what's on page 372 of the Riggers Apprentice.
It shows a plot of halyard load vs. LOA. It looks like the load for
a 28 ft boat would be less than 1500lbs, it's a small graph to
interpolate so hopefully I over estimated a little.
FWIW the title at the top of the page for the 4 different loading
graphs is "Lewmar's Formulas", I could not find anything
particularly useful on the Lewmar web pages.
Note that for a turning block like the 90 degree one on our
halyard the load on the block the load will be about 141%
of the halyard load. (see tables from previous post or this link
http://www.harken.com/charts/blockloadvangle.php)
This table shows which Harken Blocks to use vs Maximum "P" Dimension of your main sail:
http://www.harken.com/charts/BBusechart.php
I will probably be using Garhaur blocks rather than Harken since
they are more in my price range and I think they are well made
and the best value.
Rich Abato
Nordic Tug 34 Tanuki
Previous Owner Of CD36 Mahalo #163
Southern Maine
http://www.sailmahalo.com
Nordic Tug 34 Tanuki
Previous Owner Of CD36 Mahalo #163
Southern Maine
http://www.sailmahalo.com
- bottomscraper
- Posts: 1400
- Joined: Feb 5th, '05, 11:08
- Location: Previous Owner of CD36 Mahalo #163 1990
- Contact:
Except it's for sheet loads not halyard Not that it's bad info!rorik wrote:Mast height, sail area, wind strength, halyard routing, type of line and more all play a part...... there are easier to read charts and fairly easy formulas on the link I posted above.
Rich Abato
Nordic Tug 34 Tanuki
Previous Owner Of CD36 Mahalo #163
Southern Maine
http://www.sailmahalo.com
Nordic Tug 34 Tanuki
Previous Owner Of CD36 Mahalo #163
Southern Maine
http://www.sailmahalo.com
Sheets, halyards, tweakers.... the important thing is the formula. Not the name of the line to which you apply the formula. A 1000 pound load on a halyard turning 180 degrees over a sheave is going to have exactly the same effect as a sheet having a 1000 pound load and turning 180 degrees on a turning block - assuming you use the same size line and blocks for each. The formula will tell you what size line and block to use for a given load.bottomscraper wrote:Except it's for sheet loads not halyard Not that it's bad info!rorik wrote:Mast height, sail area, wind strength, halyard routing, type of line and more all play a part...... there are easier to read charts and fairly easy formulas on the link I posted above.
What I did to calculate the size of line and blocks I would need when I replaced all my running rigging was this:
Jib is 216 sqft- multiply sqft x max wind speed (before I reef that jib: 20knots) - square that - multiply by 0.00431 - that means I need a sheet that will have a SWL of at least 373 pounds. Add the physical weight of the sail and the halyard itself - and you need a halyard with a SWL of ~400 pounds. Add 50% to that for some safety - or even 100%. So your halyard and/or sheet need to have a SWL of 600# or 800#. I see no reason for the halyard to be calculated any differently than a sheet. It does the same thing, just from a different angle.
Here's the formula I used:
SL = SA x V² x 0.00431
SL = Sheet Load
SA = Sail Area
V = Velocity (wind speed)
I'm disinclined to acquiesce to your request. Means no.
- bottomscraper
- Posts: 1400
- Joined: Feb 5th, '05, 11:08
- Location: Previous Owner of CD36 Mahalo #163 1990
- Contact:
Ahhhh the light goes on!rorik wrote:
Here's the formula I used:
SL = SA x V² x 0.00431
SL = Sheet Load
SA = Sail Area
V = Velocity (wind speed)
Thanks!
Rich Abato
Nordic Tug 34 Tanuki
Previous Owner Of CD36 Mahalo #163
Southern Maine
http://www.sailmahalo.com
Nordic Tug 34 Tanuki
Previous Owner Of CD36 Mahalo #163
Southern Maine
http://www.sailmahalo.com