Mast sidestays released on dry dock

justsomeguy · Jan 3, 2020

AndrejSail said:
I ve heard that the sailboat on land may have a different shape and consequently the standing rigging can change....

This is true.

dlochner · Jan 3, 2020

How much less tension?

Yes boats do change shape when they are out of the water. The hull tends to settle down over the keel, making a bit wider with the freeboard a bit shorter. Once back in the water the weight of the keel pulls things back in to shape. The amount of distortion on land is based on the boat's scantlings (hull and deck thickness) and how the boat is blocked and placed on the jack stands or cradle.

Will Gilmore · Jan 3, 2020

Yup.
If your boat is sitting appropriately on her keel and there is adequate bracing at the bow and stern with three or more stands along her beam, you should have nothing to worry about. She'll reshape herself when back in the water.
On the other hand, if she's sitting too hard on her jackstands and not enough on the keel, you may be seeing the keel dropping and distorting the cross section shape too severely. Look for signs that the pads on your jackstands are indenting the chine. Some people refer to it as oil canning, but that's actually a little different.

-Will (Dragonfly)

Tom J · Jan 3, 2020

Don't be tempted to adjust your rigging while the boat is on the hard. The same holds true for your prop shaft. Wait until the boat has been in the water for a while before checking prop shaft alignment.

Will Gilmore · Jan 4, 2020

Do you have pictures of your boat on her stands? Something like this

-Will (Dragonfly)

dlochner · Jan 4, 2020

AndrejSail said:
Thank you for your quick answers!

Is difficult to say. The lower shrouds are almost released. Similar when sailing upwind.

I ve noticed that one of the back jack stands band the boat a little bit, so I have dificulties to open the door of the aft cabin. The forweard two seems OK, they are placed in line with sidestays.

Thanks!

If there is a lot of slack in the leeward shrouds when sailing upwind, there is too little tension on the rig. Right now, I'd just leave it alone and retune the mast when the boat is back in the water. Since the sails are not being used, the pressure on the rig is minimal, so the mast should be safe. There may be some pumping or vibration in a strong wind, but I wouldn't worry about it.

The difficulty opening and closing the door suggests the boat may not be blocked properly. There should be a stand every 8-10 feet per side, so your boat would need 4 or 5 stands on each side. Put a level on the boat to see if it is out of level. It should be within a degree or two of being level across the beam. Along the length of the boat, it should be level or with the bow slightly raised to help water run off to the scuppers.

Brownell is the company for boat stands. There is a lot of good information on their site.

Brownell Boat Stands | Where Safety and Quality Stand First

Brownell Boat Stands are where quality and safety stand first. Get you and your team trained in the Brownell Safety System. Made in Mattapoisett, MA, USA.

boatstands.com

Will Gilmore · Jan 4, 2020

Stands tied together in a welded frame like that are nice. I can't tell for sure, but the contact for the pads looks ok. There should be a support at the stem. The stern support went in too late. If they could tighten it (lift it) just a little after it's been in for a few days or a week, slowly get it back to where it might have been if they had put it in from the beginning, that would be good. Otherwise, she looks well supported.

-Will (Dragonfly)

dlochner · Jan 4, 2020

The rule I cited earlier is for jack stands which are independent stands. You have what we call a cradle, which is a much better system than jack stands. Jack stands are less stable than cradles. I had a boat fall over once on jack stands.

The cradle pads should be underneath bulkheads, if at all possible, and the weight of the boat should be supported by the keel. Doing so should reduce some of the hull sagging around the keel. It looks to me, like the boat is a little far forward on the cradle. The center of gravity should be directly over the center of the cradle. This should distribute the weight more evenly and make it balance better in the cradle.

Support under the bow would be a good idea to keep the boat from tipping forward. If the boat was moved back in the cradle, the bow and stern supports might not be needed.

Any change in hull shape while out of the water will be small, or should be small, maybe a ¼" or less, but just enough to make some doors and drawers difficult to open or close. Once back in the water, everything should settle back into place.

Tally Ho · Jan 4, 2020

4 stands for a 42-foot boat seems like way too few.

I use eight, plus one under the bow, on my 32-footer....4 on each side.

Greg

dlochner · Jan 4, 2020

Tally Ho said:
4 stands for a 42-foot boat seems like way too few.

I use eight, plus one under the bow, on my 32-footer....4 on each side.

View attachment 173526

Greg

Greg's boat is blocked properly. Keel blocked at forward and aft end, a jack stand every 8 feet. If the forward 2 stands were moved forward, then the bow stand might not be necessary, as it is, it is probably safer with the 9th stand.

The OPs boat is on a cradle which is a more secure way of storing a boat on the hard. Additional side supports are necessary because the uprights are locked into place by the frame. In contrast, jack stands can move and when they do the boat is off balance and can fall over. Having more stands, reduces the load on any one stand, reducing the hazard if one stand should fail.

Stands can move for several reasons, the most obvious is something backing into the stand and knocking it down. Another is wind load. In a strong wind the boat can rock and the rocking can cause a stand to start walking and skidding away from the boat. Ice, soft ground, and heaving frozen ground can also move the stand.

Tally Ho is secure because the keel is blocked in 2 places so the boat can't rock fore and aft. The jack stands are chained together at the mid point, so they are less likely to walk and dance around. Some stand manufacturers secure the stands at the pads, this allows the stand to dance more and if it pulls away the stand can fall. Finally, there are enough stands so that if any one of them failed, the boat would remain upright.

In the photo, this boat was not blocked properly. There was only 1 keel block, 5 jack stands, one under the bow and 2 on each side of 30 ft boat, and the stands were chained at the top. We believe that during a windstorm, the boat began to rock fore and aft because of the single keel block. That rocking caused the stands to begin moving, in particular the forward port stand, eventually, that stand fell, the chain pulled the pad off of the forward staboard stand and the boat fell over. The handle for the starboard pad embedded itself into the hull on the port side. I'll not use jack stands again for long term storage.

Davidasailor26 · Jan 5, 2020

Tally Ho said:
4 stands for a 42-foot boat seems like way too few.

I use eight, plus one under the bow, on my 32-footer....4 on each side.

View attachment 173526

Greg

For our 37 foot boat our yard uses a cradle with 10 stands.

Not sure all 10 are really needed, but the OP’s with just 4 looks a little concerning. Like dlochner said one on the bow would help, given that the forward most stand on the cradle is so far back.

In any case my guess is it’ll come back to the right shape once back in the water. Just check that there are no cracks around any stands, keel, or bulkheads, and keep the pictures of how it’s cradled just in case.

DougM · Jan 6, 2020

This is what can happen when the person who shrink wrapped the boat disconnected the lower shrouds for some unknown reason, and a spring windstorm comes through.

Tom J · Jan 6, 2020

DougM said:
This is what can happen when the person who shrink wrapped the boat disconnected the lower shrouds for some unknown reason, and a spring windstorm comes through.View attachment 173598

Something like this happened when I had my boat on the hard in Florida years ago. A crane pulled up to the boat in front of me and two guys proceeded to disconnect all the standing rigging while the crane operator was positioning the crane. Suddenly, the mast started falling towards me, and I ducked down into the companionway. When the dust settled, the crumpled mast lay on the ground between my boat and the one next to me. Oops!

markwbird · Jan 6, 2020

The hull shape does change when the boat is on the hard. As a side note this is why you should not try to align the prop shaft when the boat is out of the water.

shemandr · Jan 6, 2020

In the second pic showing the OP's boat from the bow, I think I see distortion in the hull right around the keel. This indicates to be that the weight of the boat is on the keel as it should be. The bottom of my Mark 25 would distort 4 " or more as the keel was set on the blocks. I commented on that and the yard worker said "... that's not as bad as many of the other boats." Cradles are nice but if you are using one that wasn't made for your boat the uprights may be in the wrong place. They should be where the bulkheads are. And again if the cradle isn't for your boat the width of the boat may have the cradle risers too far towards the topsides or too close to the keel. Either is a problem.

Tom J · Jan 6, 2020

A few years ago, I noticed some serious "oil canning" of the hull at the aft most stands supporting my C310. After consulting the owner's manual, I realized the aft stands should have been placed 1' ahead of the stern cleats, where a bulkhead is located. The other two side stands are placed under "sling" markers, where other bulkheads are located. No more oil canning.

Mast sidestays released on dry dock

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