Loose lee shroud

Moderator: GreenLake

Loose lee shroud

Postby Tipster1 » Sat Aug 26, 2017 8:22 am

After a season in the driveway my DSII is finally in the water. After floating on mooring for a week, I snugged up the shrouds and went for a sail. My DIY jib snuffer (quick down-haul) worked perfectly. Thanks to who-ever suggested that.

With a light wind, the lee shroud was pretty loose so I re-tightened. Still kind of sloppy. I'm wondering how much of this is coming from stretching stainless and how much might be coming from hull flex. Boat still has original rigging with single spreader arrangement. If hull is flexing, has anyone ever installed compression prevention strut horizontally across cuddy at level of chain plates? I can picture it limiting hull flex.
Tipster1
 
Posts: 107
Joined: Fri Apr 27, 2012 9:37 am
Location: PA/NJ

Re: Loose lee shroud

Postby DigitalMechanic » Sat Aug 26, 2017 11:32 am

The lee shroud should go slack. I run around 180lbs of tension the shrouds on my DSII (which I think may be more than most), and in moderate winds it goes a little slack/sloppy. If you are talking about 5mph wind, and it is going slack you may consider tightening it up some.

There are several rigging guides, but I tend to follow the one Dave Keran made for North Sails (even though I have cheap Intensity sails on my boat, it seems to work fine for me). If you have sails that came with a rigging guide try to follow it, or post the guide for them so we can help :wink:

If you want to follow Dave's guide in detail it is located here...
https://northsails.com/sailing/wp-content/uploads/2017/05/north-daysailer-tuningguide.pdf

I think Dave's guide is probably the best if you are not interested in tightening your rig to 300-400lbs (and most will not unless they are serious about racing). The guide recommends 300-320lbs, but I have found the boat cruises fine rigged at 180lbs on the shrouds using to Dave's guide (and I am not worried about snapping a chainplate through the gunwale). Here is my abbreviated version/translation of the standing rigging setup...

Centering fore/aft:
To get the fore/aft positioning of the mast you can lash a tape measure to the main halyard and run it up to the top. You should have roughly 25 feet from the top of the mast to the top of the transom. You may start at 24' 11" as you will ultimately put an inch of prebend in the mast and make adjustments to the forestay, which should pull it back once you start tightening everything down.

Centering starboard/port:
You can measure how centered the mast is after your tightening adjustments by taking your main halyard and pulling it to the gunwale next to the chainplate and marking it with your thumb. Then walk to the other side of the boat and see if the spot where your thumb is too short or too long. You will know what side to tighten (or loosen) more until you get it centered.

Prebend:
When all said and done, you should have about an inch of prebend. you can measure this by pulling the main halyard down to the gooseneck (tight), and measuring the gap between the mast and the halyard up by the spreaders. You should have about an inch gap.

You can measure with a "Loos Gauge", but when I got to this point I had 180lbs on the shrouds and 110-120 lbs on the forestay, and 1" prebend, 25ft from top of mast to transom. Could it be tightened more, yes. But where it sat, everything was in spec, so I left the tension at what I suspect the racing folks would tell you is minimum spec to make the boat sail correctly (actually my buddy races and he said he would tighten the rig considerably, lol... but was fine for cruising, and sailed correctly). If I wanted to race it with the rigging at 320lbs and 210lb forestay, I would fabricate elongated chainplates to distribute the load across the gunwales more for extra support.

Rigging tips:

1. Need to tighten more and cannot... If you cannot tighten anymore and feel you need to still, it means your mast is too short. My boat has been de-masted at least once by me and once by someone else... oops. You can shim the mast from below in the cuddy if you need to.

These work great http://www.drmarine.com/proddetail.asp?prod=DS207
Just take a grinder and blow away the extrusions.

Also, many have used wood to shim with and reported good results, but you will have to inspect it frequently. I have a wood shim on my boat and works fine. I just inspected it last week while doing some other repairs on the boat and is in good shape. Been there for 2 years, sandwiched between 2 shaved mast castings (kind of like a wood filler) :wink:

Also, if you have been de-masted there is a good chance the screws that hold the casting into the cuddy floor are stripped. You may inspect them if you make it that far to make sure you do not need a wider screw to fill the holes now.

2. Forestay tension... Do not worry about getting an exact tension on the forestay. It is going to land where it lands after you do all the other adjustments correctly. The reason to adjust the forestay is to keep puling the mast back to the 25' from transom mark. Think of your goals as this...

Adjust shrouds until you get the 1 inch prebend in the mast
Adjust forestay to keep mast tip at 25' from transom

You do not need a Loos gauge to do this, just a halyard and a tape measure (but if you are nosy like me and want to know the actual tension, then a Loos gauge is your friend)

Once you hit those 2 goals everything should be falling into place :wink:
DigitalMechanic
 
Posts: 373
Joined: Sat Nov 07, 2015 7:00 am
Location: Jacksonville, FL

Re: Loose lee shroud

Postby GreenLake » Sat Aug 26, 2017 2:18 pm

Nice post!

May I suggest epoxy coating any wood-shims you might be using in the cuddy?

Get some laminating epoxy, West / MAS / System Three and carefully measure and mix to spec. Coat all (six) sides of your piece of wood. A second coat does not hurt. If you need to drill holes for throughbolts, drill them very slightly oversized and coat their insides as well. If you have holes for screws, wax the screw and insert after you added the epoxy. Screw should still come out after the epoxy is cured.

Even if inside the cuddy, add a coat of spray paint to prevent degradation of the epoxy by whatever UV gets in there if someone leaves the cuddy doors open.

With that done, your piece of wood should be set for the remaining lifetime of your boat - as long as you don't breach the epoxy seal.

Finally, epoxy tends to have a generous shelf-life, so don't fret about left-overs; you'll find a use for them.

(Alternatively, if you have frequent need for epoxy glue, rather than as laminating resin, you could get the caulk-gun cartridge, for example GelMagic by SystemThree - while a glue, it still does a good enough job at wetting out a surface, and the mixing tip means you don't need to measure and mix by hand, but you'll need a new tip for each job and you waste the unmixed epoxy in the tip).
~ green ~ lake ~ ~
GreenLake
 
Posts: 4983
Joined: Mon Jun 18, 2007 3:54 am

Re: Loose lee shroud

Postby Tipster1 » Mon Aug 28, 2017 7:46 am

Thank you both for your replies. No one is saluting my compression strut idea so far. Is it illegal in class? It would give me a coat rack, too.

Just out of curiosity I might get my hands on a loos gauge. (Or a tuning fork? :) )

I already shimmed my mast base with some pvc trim material.
16041626
Tipster1
 
Posts: 107
Joined: Fri Apr 27, 2012 9:37 am
Location: PA/NJ

Re: Loose lee shroud

Postby DigitalMechanic » Mon Aug 28, 2017 9:16 am

Tipster1 wrote:No one is saluting my compression strut idea so far. Is it illegal in class? It would give me a coat rack, too.


Trying to wrap my head around that one, or why you would have hull flex? When I first got my boat, I learned a lot of lessons the hard way very quickly. In my particular case, I realized pretty fast that I pretty much bought a hull and spars, and everything on them has been replaced since (which was not in the original plan) :wink:

With all new standing rigging snugged up the way I have it, I do not notice hull flex (at the chainplates). I do not remember anyone reporting that either (but could be wrong). One place the hull will flex is underneath the boat (40+ year old boat might have some soft spots on the bottom). In particular, I did some trailer work about a year ago, replacing the bunks with 7 ft 2x4s. That was a major upgrade from what I started with (trailer of shame), as the boat was sitting on the corners of the bunks :shock: With the 7ft'ers in there and the boat sitting flat on them, I noticed that because they did not go all the way back to the transom there was a slight sag in the hull right past where the bunks stopped. A problem that has since been remedied with 11ft 2x6 bunks. The old girl now has the support she needs :D

For grins and giggles...
2451

Anyway, wayyyyy...... off topic, but the "hull flex" idea got me thinking about it so though I would mention :wink:

Back on topic, lol... Did I mention that I had a rigging failure? (that was not a fun day on the water) You may upgrade your rigging if you are unsure of it...

Tipster1 wrote:Boat still has original rigging with single spreader arrangement.


Parts are here:
http://www.drmarine.com/proddetail.asp?prod=DS800A
http://www.drmarine.com/proddetail.asp?prod=DS204HD

The lengths are already cut to spec and ready to be clipped on, adjusted, and go.

If you are this far into it, I would highly recommend inspecting the rivets holding the tangs to the boat's mast as well. The original rivets (if still present) are going to be 40+ year old and made of aluminum. I could pull some of the ones on my mast out by hand :shock: ...which led me to ultimately replacing them all for piece of mind. I switched to stainless rivets (which is debatable), but if you do I believe there is a coating that you can put on them to help mitigate Galvanic corrosion. The name of this coating evades me at the moment, but I bet that someone will chime in with it.

Just thinking out loud now, but the chainplates are just outside of the cuddy's bulkhead, which in theory should be providing the support already where you propose to install the "crossmember" (is that what we would call it?). Is there any visible damage to the bulkhead area (cuddy opening, inside or out)? Still trying to wrap my head around why this area would "flex". Or maybe it does and I have never noticed it?

-Paul
DigitalMechanic
 
Posts: 373
Joined: Sat Nov 07, 2015 7:00 am
Location: Jacksonville, FL

Re: Limiting hull flex

Postby GreenLake » Mon Aug 28, 2017 6:59 pm

There are many components to hull flex.

The obvious one is the distance from deck to keel for deck-stepped mast. Compression posts take care of that one.

Then there's flex from the hull getting wider. For the DSII (and modern DS1) the wide "lip" around the cuddy opening and cockpit sole make it harder for the boat to get wider in response to loads. Mostly by making the deck opening a bit stiffer.

The old DS1's have the thwarts, that serve to limit how wide the boat can get just behind the cuddy.

It is certainly possible to build an arch that more directly connects the loads from the deck-stepped mast to points near the chain plates. But it won't affect the bottom of the hull deforming a bit, not unless you continue said arch all around along the bottom.

Even if you do that, the boat will still flex in places. For the DS1, some people have gone to the length of adding a foam core to the hull (where it is accessible) this makes the boat reportedly much stiffer, especially also in the long flat runs of hull aft.

The DaySailer class rules mostly focus on the external lines of hull and deck, so you are free to add a roll cage or whatever on the inside of your cuddy. (There may be some restrictions on what materials may be used - carbon may be out, but cardboard is fine, and so are cardboard derivatives).
~ green ~ lake ~ ~
GreenLake
 
Posts: 4983
Joined: Mon Jun 18, 2007 3:54 am


Return to Rigging

Who is online

Users browsing this forum: No registered users and 1 guest

cron