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Boat Blocking

Recently a reader sent this question along regarding the way their boat was blocked and supported at the boat yard. This is a good post to share, and also a good time to get all the boatyards to look over the newest version of the ABYC Tech Info report TY-28, which was heavily revised in 2014.

Question: My friends and I have been debating how well my Island Packet 32 ft. sailboat is stored for the winter. I had the mast removed this year so that it could be totally inspected and upgraded as needed. You can see in the photo I sent in that I also had it shrink wrapped. The debate is over the number of jack stands the boat yard used to hold the boat upright. The yard used five stands and blocked the keel at three points. It looks OK, but my friends say that they don’t think the job meets industry standards. I can’t tell because as I look around the boatyard, I see boats of a similar length with more stands and others with the same setup. Is there actually an industry standard that addresses this, and if so is my boat blocked and supported adequately?

Great question. In fact there is an industry standard that addresses this matter and it was recently updated in July of this year (2014). ABYC Standard TY-28, which is actually a technical information report vs. a “standard”, provides guidance for boat lifting and storage. It is the only document I am aware of here in the US that addresses this matter.

As for the answer to your question, the number of stands and blocks can vary due to variables such as whether or not the boat has the mast in place or not as in your case. Other factors such as hull shape, windage, weather and ground conditions will also come into play here. That said, a quote from TY-28 should answer your question:

Boat stands should be spaced no more than 10 feet (3m) apart on centers, with the forward-most and after-most pairs of stands no more than 10 feet (3m) from the ends of the waterline. Powerboat stands should be set with the aft pair placed as close to the aft end of the waterline as structure permits, and spaced no more than 10 feet (3m) apart on centers.

The stands should balance the boat to keep it level athwartships. The boat’s weight should be borne by the blocking. Do not use the stands to support the weight of the boat unless the stand is designed for this purpose. Some boats require that the weight of the boat be supported on the chine. Use supports designed for this load.

Apply boat stands as far outboard as practical, and with the adjusting screw as close to perpendicular to the hull as practical. Sometimes it is necessary to tip the stand to make it perpendicular to the hull. Do not block more than two legs of a stand.

On vessels with extreme overhang, forward or aft, a stand(s) should be placed under the overhang perpendicular to the centerline. Do not place blocks on top of boat stands to increase their reach. Stands should not be used as jacks to raise or lower the boat. Apply boat stand(s) so that, after the blocking operation is complete, the stand screw can still be adjusted up and down.

Secure each pair of stands across the boat to prevent lateral movement. Stands that are not designed to be chained together should be installed so that the outboard edge of the pad is against a chine or spray strake to lock the pad in position and prevent it from sliding outboard. The material used to tie the stands together should be at least 3/16 inch chain. Rope or wire is not recommended as it can stretch and allow the stands to slip. Do not allow anything to be tied to the stands except the chains that hold pairs of stands together. Accidents have occurred when covers tied to boat stands have pulled the stands from under the boat.

Check stands routinely during storage season. After a period of storage, a hull may begin to flex in the way of the stand pad. If this occurs add a stand, or move stands, to bear directly under a bulkhead, stringer, or other structural member that can sustain and distribute the load. If it is necessary to move an installed boat stand, position another stand next to the stand to be moved, and chain the new stand securely in position before moving the first stand.

Additional attention to stands may be required during freeze/thaw cycles, before, during, and after storms, and on soft ground. On soft ground, extra, rigid pads, such as plywood, may be required under the stand(s) to prevent them from sinking into the ground.”

Looking at the photo you sent in, it’s hard to say if the stands should be chained together. I can’t really tell from the picture you sent in if they are designed to be chained or not. It’s a question worth asking your yard manager though. Based on the fact that your mast is out and stored separately and the boat is on asphalt with wooden pads under the jack stand feet I would say that the number of stands and blocks looks adequate based on TY-28.

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