Cruisers Forum
 


Join CruisersForum Today

Reply
 
Thread Tools Rate Thread Display Modes
Old 16-05-2011, 15:32   #1
Registered User
 
hoppy's Avatar

Join Date: Sep 2009
Location: Melbourne, Australia
Boat: Jeanneau Sun Odyssey 40
Posts: 2,842
Folding Pad Eye for Gennaker Block Mounting

Is a folding pad eye with a breaking load of 4400kg sufficient for mounting a gennaker/code zero sheet block?

I bought the pad eye originally for the jack lines but now I am wondering whether to install them in a position when they can be used for a gennaker (whenever I get one).

I am guessing that 4400kg is more than enough, but I figure it is better to find out for sure before I drill some hole

The boat is 40ft and in the manual the spinnaker size is 108sqm and I guess the gennaker would be a little less.
__________________

__________________
hoppy is offline   Reply With Quote
Old 17-05-2011, 15:00   #2
Vendor
 
witzgall's Avatar

Cruisers Forum Supporter

Join Date: Oct 2006
Location: Eastern Shore, MD
Boat: Camper Nicholson 44 Ketch
Posts: 1,773
Re: Folding Pad Eye for Gennaker Block Mounting

We have a double wichard padeye for a storm sail mounting point. I have seen others use the same, so I would go for a big double.

Chris
__________________

__________________
witzgall is offline   Reply With Quote
Old 17-05-2011, 17:39   #3
Marine Service Provider

Join Date: Aug 2006
Location: US/MX West coast
Posts: 465
Re: Folding Pad Eye for Gennaker Block Mounting

Hoppy,

I'd want to know the safe working load rather than the breaking strength before commenting.
__________________
islandplanet is offline   Reply With Quote
Old 18-05-2011, 00:23   #4
Registered User
 
hoppy's Avatar

Join Date: Sep 2009
Location: Melbourne, Australia
Boat: Jeanneau Sun Odyssey 40
Posts: 2,842
Re: Folding Pad Eye for Gennaker Block Mounting

I noticed that most blocks and other things I looked at quoted both breaking and safe working loads, but the pad eye only had breaking. Do you know how much safe working load is needed?
__________________
hoppy is offline   Reply With Quote
Old 18-05-2011, 01:30   #5
Registered User

Join Date: Oct 2007
Location: San Francisco
Boat: N/M 45
Posts: 236
Re: Folding Pad Eye for Gennaker Block Mounting

You might talk with your sailmaker and ask them what they expect the tack loads to be on that sail, and add your own safety factor.

Alternatively, you might assume the load will be equivalent to the halyard sheave or block load and select a padeye accordingly. 4400kg break load seems low to me for handling shock loads; for example, Harken specifies padeye working loads at roughly 1/2 breaking load.

- rob/beetle
__________________
beetle is offline   Reply With Quote
Old 18-05-2011, 03:31   #6
Registered User
 
Doodles's Avatar

Join Date: Nov 2009
Location: Virginia, USA & Krabi, Thailand
Boat: Wauquiez Pretorien 35; Nordica 16
Posts: 2,810
Images: 1
Re: Folding Pad Eye for Gennaker Block Mounting

If I'm reading this right it looks like the working load (funct. ?) is about 55-66% of the breaking. Also, interesting that the single padeye loads are the same as the double? Am I missing something or else why spend the extra on the double. Maybe on the double it is per eye?

Wichard Pad Eyes
__________________
Mundis Ex Igne Factus Est
Doodles is offline   Reply With Quote
Old 18-05-2011, 05:57   #7
Registered User

Join Date: Dec 2009
Posts: 3,016
Images: 4
Re: Folding Pad Eye for Gennaker Block Mounting

Does the sheet turn 180 at the block? That would double the load.
__________________
daddle is offline   Reply With Quote
Old 18-05-2011, 09:08   #8
Registered User

Join Date: Oct 2007
Location: San Francisco
Boat: N/M 45
Posts: 236
Re: Folding Pad Eye for Gennaker Block Mounting

Quote:
Originally Posted by daddle View Post
Does the sheet turn 180 at the block? That would double the load.
The tack line would normally turn 90-100 degrees at the tack padeye, assuming the tack line is adjustable from the cockpit, and that turn increases the load seen at the padeye by 1.4.

A 180 degree turn is more likely seen by things such as genoa sheet and spinnaker sheet turning blocks, as well as main and jib halyard sheaves.

- rob/beetle
__________________
beetle is offline   Reply With Quote
Old 18-05-2011, 09:49   #9
Registered User

Join Date: Dec 2009
Posts: 3,016
Images: 4
Re: Folding Pad Eye for Gennaker Block Mounting

Quote:
Originally Posted by beetle View Post
The tack line would normally turn 90-100 degrees at the tack padeye, assuming the tack line is adjustable from the cockpit, and that turn increases the load seen at the padeye by 1.4.

A 180 degree turn is more likely seen by things such as genoa sheet and spinnaker sheet turning blocks, as well as main and jib halyard sheaves.

- rob/beetle
OP wrote "sheet"
__________________
daddle is offline   Reply With Quote
Old 18-05-2011, 09:52   #10
Registered User

Join Date: Oct 2007
Location: San Francisco
Boat: N/M 45
Posts: 236
Re: Folding Pad Eye for Gennaker Block Mounting

Quote:
Originally Posted by daddle View Post
OP wrote "sheet"
Oops! - quite right. Then the load may double.
__________________
beetle is offline   Reply With Quote
Old 18-05-2011, 15:17   #11
Marine Service Provider

Join Date: Aug 2006
Location: US/MX West coast
Posts: 465
Re: Folding Pad Eye for Gennaker Block Mounting

Load will be dependent on a lot of factors:
Sail size
Sail material (nylon absorbs some loads)
Wind
Tenderness or stiffness of boat (this is why cat sails are so heavily loaded - the boat doesn't heel)

You mentioned your spinnaker is 108m and that you expect the gennaker to be smaller which is true. If we were selecting a foil-less furler for the boat we'd probably be looking at something with at least 3500lb working load.

You may want to consult a rigger for advice on which fitting to procure.
__________________
islandplanet is offline   Reply With Quote
Old 17-10-2017, 14:54   #12
Elvish meaning 'Far-Wanderer'
 
Palarran's Avatar

Cruisers Forum Supporter

Join Date: Jan 2008
Location: Me - Michigan / Boat - Tenerife
Boat: 56' Fountaine Pajot Marquises
Posts: 2,641
Re: Folding Pad Eye for Gennaker Block Mounting

I'm going to do the same thing for my spinnaker tack point on each pontoon near the tip. The wichard pad eye that I ordered has a working load of 2400kg and a breaking load of 4500kg. The tack line is 14mm and looking at charts, it's tensile strength isn't far off the working load. The boat has the same pad eyes right now for the spin sheet block.

I'm wondering two things;
1- Do you think these pad eyes are strong enough for a spinnaker tack point - no idea of the sail size, but it's pretty big.

and
2- What kind of backing plate do you use? Should I use a solid piece of aluminum? Do you bed this backing plate into fiberglass if the surface isn't completely flat? I'm less worried about the pad eye breaking as the fiberglass structure pulling apart.
__________________
Not all who wander are lost

http://www.sailblogs.com/member/palarran/
Palarran is offline   Reply With Quote
Old 17-10-2017, 16:13   #13
Registered User
 
UNCIVILIZED's Avatar

Join Date: Jun 2014
Location: Up the mast, looking for clean wind.
Boat: Currently Shopping, & Heavily in LUST!
Posts: 5,629
Re: Folding Pad Eye for Gennaker Block Mounting

Realistically, for a mounting point for a spin sheet on a 40' cruiser, a 2,000 - 2,500kg working load is enough. Assuming that is that you douse the kite by the time the winds get up to 20kts/20kts+. It's going to need a good backing plate though, & to be mounted in an area where there's enough structure to carry a lot of load.

Some of this is experience based, & some's simple math. Since if you have a 125sqm kite, & it's blowing 20kts, the sheet load will be around 1,200kg (in theory, less in practice). You can work out the math here Harken Sailboat Hardware and Accessories

The one catch though is that you need to align the padeye so that it's properly oriented to optimally take the load. As the rated load for any padeye differs depending on the angle of pull that it's subject to. So if in doubt, you can't really go too big, particularly if you don't know at what angle the BL or SWL was calculated & tested at.

Quote:
Originally Posted by Palarran View Post
I'm going to do the same thing for my spinnaker tack point on each pontoon near the tip. The wichard pad eye that I ordered has a working load of 2400kg and a breaking load of 4500kg. The tack line is 14mm and looking at charts, it's tensile strength isn't far off the working load. The boat has the same pad eyes right now for the spin sheet block.

I'm wondering two things;
1- Do you think these pad eyes are strong enough for a spinnaker tack point - no idea of the sail size, but it's pretty big.

and
2- What kind of backing plate do you use? Should I use a solid piece of aluminum? Do you bed this backing plate into fiberglass if the surface isn't completely flat? I'm less worried about the pad eye breaking as the fiberglass structure pulling apart.
For a tack padeye on a Code 0 personally I'd want something stronger. As even with zero wind in the sail you'll be putting quite a lot of load onto the halyard, & thus the padeye, particularly if it's a 2:1 halyard. And then you have to add in the loads created by the wind in the sail. Ergo, go up a size or two.

For backing, aluminium, G-10, FRP plate, or stainless works. Though if there's any concern about the strength of the deck in that region you'll want to;
- make sure the laminate's not cored
- add some extra glass to the deck's underside, possibly tying things into the hull with reinforcements. And or, also adding knees or ring frames. The latter are KISS to install, & pretty dang effective.
- at a minimum bed the backing plate in structural bog (epoxy mixed with chopped or milled glass fibers). And bonding a G-10 or FRP plate (aluminum too) in place with bog would be preferable, as this will help spread out the load even better, by tying the backing plate into the deck's structure. Thus strengthening it.
- Also, bevel the edges of any backing plates. It reduces the stress risers at their edges (point loadings).

Bottom line on all of these questions though is if in doubt, go up a size. As the extra $20-$30 that you spend on the larger padeye is cheap compared to 99% of everything else onboard. And you can't even by a date/the Mrs. dinner at a resturant for that, so...
__________________

The Uncommon Thing, The Hard Thing, The Important Thing (in Life): Making Promises to Yourself, And Keeping Them.
UNCIVILIZED is offline   Reply With Quote
Old 17-10-2017, 17:31   #14
Elvish meaning 'Far-Wanderer'
 
Palarran's Avatar

Cruisers Forum Supporter

Join Date: Jan 2008
Location: Me - Michigan / Boat - Tenerife
Boat: 56' Fountaine Pajot Marquises
Posts: 2,641
Re: Folding Pad Eye for Gennaker Block Mounting

The pad eye I ordered is the largest Wichard makes. Also, this isn't for a code 0 but a standard Asym. While winds can get strong quickly, we always douse the spinnaker when the apparent wind exceeds 16 knots. This doesn't affect the boat much as my main and jib will propel me as fast in winds this speed anyway.

I wish I knew the sail sf so I could use that calculator. Though as I said, we have been using the same pad eye for the spin sheet since purchased. Also, the prodder currently uses two mounted on the hull low in order to support it. Probably the loads are 80/20 on those, so it's not much different.

Good advice on the backing plate. That is what I mostly was thinking.
__________________
Not all who wander are lost

http://www.sailblogs.com/member/palarran/
Palarran is offline   Reply With Quote
Old 17-10-2017, 17:40   #15
Elvish meaning 'Far-Wanderer'
 
Palarran's Avatar

Cruisers Forum Supporter

Join Date: Jan 2008
Location: Me - Michigan / Boat - Tenerife
Boat: 56' Fountaine Pajot Marquises
Posts: 2,641
Re: Folding Pad Eye for Gennaker Block Mounting

Actually, after looking at that Harken calculator, the better one would be main sheet load. For my main, it's approximately 1224 kilos at 16 knots.

Harken Sailboat Hardware and Accessories
__________________

__________________
Not all who wander are lost

http://www.sailblogs.com/member/palarran/
Palarran is offline   Reply With Quote
Reply

Tags
gennaker

Thread Tools
Display Modes Rate This Thread
Rate This Thread:

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


Similar Threads
Thread Thread Starter Forum Replies Last Post
For Sale: Cruising Gennaker DCGSAILING Classifieds Archive 2 21-01-2011 08:55
Spinnaker/Gennaker ilikeraresteak Deck hardware: Rigging, Sails & Hoisting 10 28-10-2008 09:07
Gennaker and Snuffer Rigging Noob7_0 Deck hardware: Rigging, Sails & Hoisting 12 11-12-2007 19:11
Pad eye as a wire fairlead? rebel heart Deck hardware: Rigging, Sails & Hoisting 12 12-11-2007 11:51
Spinnaker as Gennaker? Will Burton General Sailing Forum 18 17-04-2006 05:37



Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -7. The time now is 20:54.


Google+
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.

ShowCase vBulletin Plugins by Drive Thru Online, Inc.