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Blocking Ashore: The Right and Wrong Way

By badriance - Published October 13, 2009 - Viewed 14445 times

In April of 2006, a strong northeaster howled through the mid-Atlantic with winds gusting to 50 knots and three inches of drenching rain. Since it was the start of the boating season, preparations had been already underway in Middle River, Maryland to begin launching hundreds of boats that were stored ashore. One sailboat wouldn’t make it. While getting other boats prepped for launching, the yard moved the boat to a different location temporarily and neglected to chain the two aft pairs of stands together. And they didn’t lay down plywood to prevent the stand’s leg from sinking into the softening ground. The long deluge, along with the howling winds, caused the stands to sink and pull away from the boat. One powerful gust was all it took to knock the boat over, snapping its keel and rudder, cracking the hull, and breaking internal fiberglass tabbing. The investigator noted that the yard almost always followed the ABYC TY-28 standards for boat storage; almost being the key word. Knowing that strong northeasters were possible even in April, the yard should have used chains and plywood when they temporarily blocked the boat.


A good boatyard has long experience with proper blocking techniques and knows how to support boats of all types. And most yards will tell you that the absolute best support is from a custom-made cradle that supports all areas of a boat the right way in the right places. Bulkheads and engines are areas where support should be placed, and cradles do a great job. But since they are expensive to build and cumbersome to store during the season, cradles are pretty rare. Homemade cradles often are inadequate, though shipping cradles are OK if they are reinforced. Using a cradle not designed for your boat isn’t recommended since the boat may not be supported correctly.


The majority of boatyards use jack stands, and are usually competent in blocking boats. And in fact, some yards say that proper blocking is as much science as art -- science for knowing where the boat’s bulkheads are for stand placement, and art for knowing the nuances of a boat’s keel configuration, engine weight, or other subtleties. The keys to proper jack stand use are placement and positioning. The weight on the pads should be in a downward direction, not out; pads that simply lie against the hull can easily slip away. Jack stands also have to be chained (rope might stretch and is unsuitable) together under the boat tightly to keep them from shifting. Boats need to have at least two jack stands per side, and for sailboats, they should be no farther than 10 feet apart. Long overhangs may require extra stands. Blocks should never be used under a stand or on top of the pads to make it taller. These guidelines may have to be adjusted upwards during storm season. Some jack stands are angled and some are vertical; each has its use and they are generally not interchangeable. Rigid pads should be used under jack stands where the ground is soft or may become soft. (Note: Even asphalt can become soft in high temperatures).


One point that is important to keep in mind is that jack stands are designed solely to hold a boat upright and level. The boat’s weight should rest on its keel, and keels should rest on wooden blocks. Wood, unlike brick, won’t shatter. Cinderblocks can crumble and should not be used. On a powerboat, incorrect placement of blocks can lead to hull damage or worse, the blocks can punch through the hull. Sailboat keels need to be supported with wide blocks along the keels. There are a few boats (very few) that are not designed to rest their weight on their keel. If you’re not sure, check with the manufacturer or a knowledgeable marine surveyor. Outdrives and outboard engines should have their weight resting on a block, not simply hanging from the transom. Powerboats typically require extra support beneath the engines.




All it will take is

a little movement

to cause the wood

to fall out, which

will at the least gouge

the hull and at the worst

topple the boat.



The boat must be level to allow water to drain. (Note: Some boats may have cockpit drains in the forward part of the cockpit and need a slight tilt downward toward the bow.) Make sure the yard knows where your drains are before they block it.


It’s a good idea after the boat’s been blocked to look for depressions in the hull where the stands may be pressing too hard. If that’s the case, don’t try to adjust the stands yourself -- notify the yard. Doing it yourself could topple the boat, damaging your boat, or worse, injuring yourself. Once you’re satisfied that the blocking is OK, revisit your boat in a week or two and see if settling has made any differences.


PROBLEM #1: The majority of boats need their weight

to be supported by blocks along their keel. But some

boats, like this one, don't have adequate strength in

the hull to support the boat. When that happens, the

blocks can punch right through the hull. Find otu from

your manufacturer or ask a knowledgeable marine

surveyor if your boat is one of these.

PROBLEM #2: Cinder blocks should never be used to

support a boat since they can easily crumble; wooden

blocks are the best choice.


Once the boat is blocked, it’s critical to make sure covers are not tied to the stands; the BoatUS claim files have accounts of strong winds and flapping covers pulling out jack stands, causing boats to fall over. Covers also have to be fitted so as not to pool water or snow; the added weight might be too much for the stands or blacks. Cockpit scuppers and drains need to remain open for the same reason.


Trailers are a good alternative for many smaller boats since rollers and pads are usually adjustable and can be moved to critical weight-bearing areas. Trailers for deep-draft sailboats are the exception -- they’re designed for wind coming from ahead, not abeam. They can be used if jack stands are positioned along the hull. Removing the mast is also a good idea for trailerable sailboats as it substantially reduces windage.


Do’s and Don’ts


v     To be safe, winterize your boat before haul-out. The moderating influence of water won’t be present ashore and a sudden freeze is more likely to crack an engine black or ruin a freshwater system.


v     Inspect the blocking periodically. Check to see that the pads are not depressing the hull. Also, look for rust on the jack stands, especially at the junction of the leg brace. Badly rusted or bent stands should be replaced.


v     Jack stands aren’t designed to be used to suspend a boat in mid-air -- boats must be supported by blocks along the centerline of the boat.


v    Cradles are usually preferred over

       jack stands and blocks, but using

       a poorly made cradle or one that

       was not made for your boat is   

       asking for trouble. This cradle was

       not strong enough for the size of

the  boat (note the tiny pads) and all it

       took was a thunderstorm to knock 

       the boat over, causing extensive damage.


v     Use safety chains on all stands, tightly chaining pairs together from port to starboard. Rope is not suitable since it stretches.


v     Don’t try to move or adjust a jack stand that is in use. Get a yard worker to do it.


v     Jack stands should be used in pairs, one placed port and one placed starboard for every 10 feet of a boat’s length, with a minimum of four jack stands per boat. An additional stand may be needed for the bow. Extra jack stands may be needed for fin-keel or bow-heavy sailboats. 


v     Never allow anything (such as boat covers) to be tied to the jack stands. A strong wind can move the stand, causing the boat to topple. The cover can be tied under the boat, or partially filled plastic bottles can be hung from it to keep it taut.


v     If you’re concerned about storms, you may want to consider having the mast removed. It goes without saying that roller-furled sails should be taken down; it reduces windage and a flogging sail can bring down the whole boat.


v     Jack stands should be placed so the adjusting screw is as perpendicular to the hull as possible and they should be positioned outboard, as far as possible.


v     Plywood should be placed under the jack stands if the ground is soft -- even on asphalt in hot climates.


For detailed information on how to formulate your winterizing plan, Click Here to request your free copy of Seaworthy’s acclaimed Winterizing Your Boat manual, a comprehensive guide to prepping your boat from hull to engine.


To supplement your winterizing plan, Download Seaworthy’s Winterizing Worksheet; the ideal checklist for organizing actions taken while securing your boat, keeping track of needed materials, and keeping inventory of all equipment stored ashore.


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