Paging though my manual I found an illustration suggesting that 4"x4" blocks should be placed under the rubrail between the hull and lifting straps. In my limited experience, I haven't seen this being done. Is this commonly done? I could see it being good practice, but is it particularly necessary? I don't imagine my marina guys would be too excited about having to juggle 4 blocks precisely under the rubrail before and after lifting the boat.
Lifting strap blocking
- Thread starter jdrutten
- Start date
It could be a precaution, but it would depend on how wide the lifting slings are. Most yards around here use Travelifts, which can spread the straps wide enough so there is no contact with the rubrail. If your yard uses a crane with slings hanging from a pipe frame, the spread of the slings is limited by the width of the frame, and may not even be adjustable. In situations like that the slings might come in contact with the rubrails and you would want blocks to keep that from happening. If that is your situation it might be a good idea to prepare the blocks ahead of time with holes drilled at each end so you could rig a line through the holes and then hang them from the lifelines. Jamming them into place when the strap is close enough to hold them but not too tight for them to fit might otherwise might be tricky.
Ask the yard if they can accommodate your boat like this :
I'm pretty sure they will be able to accommodate you.
I would be EXTREMELY cautious in placing 4 X 4 blocks just below the rub rail. A vector analysis of the straps would show that if the they were hanging VERTICALLY or, even worse, closer to the boat centreline, the inward force of the straps on the blocks would be sufficient to cave in the hull of the boat seeing as it's only about 3/8" thick near the top. You want all of the forces applied to the hull to be vertical and avoid large horizontal forces.
Further compounding the problem would be the PRESSURE on the hull at the four 4 X 4 spacers due to their much smaller surface area compared to the two belts.
Also notice the tiny LIFT stickers on your hull right under the rub rail.
I'm pretty sure they will be able to accommodate you.
I would be EXTREMELY cautious in placing 4 X 4 blocks just below the rub rail. A vector analysis of the straps would show that if the they were hanging VERTICALLY or, even worse, closer to the boat centreline, the inward force of the straps on the blocks would be sufficient to cave in the hull of the boat seeing as it's only about 3/8" thick near the top. You want all of the forces applied to the hull to be vertical and avoid large horizontal forces.
Further compounding the problem would be the PRESSURE on the hull at the four 4 X 4 spacers due to their much smaller surface area compared to the two belts.
Also notice the tiny LIFT stickers on your hull right under the rub rail.
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The 4x4 blocks are probably supposed to be a foot or so long,
Wouldn't the 4x4 blocks be a foot or more long, to spread the load out over a bigger area than the strap itself? Placing them just below the rubrail puts them essentially at the hull/deck joint. After the stem, isn't the hull/deck joint one of the strongest parts of the boat? If this wasn't the case, wouldn't the straps - with or without the blocks - simply crush the hull itself when they tightened? The straps are not putting the whole weight of the boat on the blocks - only the vector component of the straps that might (repeat - MIGHT) be pressing against the rubrail and possibly bend it. The blocks are to keep the straps away from the rubrail so it doesn't get torqued when the straps are tightened. As the pictures in Ralph's post above show, the straps on a travelift are spread wide enough to avoid the problem entirely.
I have spent 50 years as ground crew launching boats with Travel lifts and have never seen 4x4 blocks used.
Thanks for easing my anxiety. The prior owner certainly never made it past page 2 in the manual so I’ll assume that the boat has been hauled and launched upwards of 20 times without blocking. Somehow my boat still floats. I wonder if this page in the manual was suggested by the Hunter legal team.
I looked at the image and I think I know what's wrong but I was a bit confused by hunter calling a 14 inch 4 by 4 a block and then not advising how it would be attached to the boat before lifting it with straps. Another part was calling that boat 360 and the label on the drawing says 290 in green printing.
But let's face it the computer generated image was made April 13th 1999. Y2K messed it up.
But let's face it the computer generated image was made April 13th 1999. Y2K messed it up.
I've owned a 2005 Hunter 38 and a 2005 Hunter 33. Both manuals say to use these blocks. I've never had an issue in a travel lift leaving the blocks out. I think it's intended to keep the strap from applying pressure and point loading the rub rail under the straps. As shown in the pictures above, the straps clear the rub rail in most travel lifts.
Having spent many years at the marina of a Hunter dealer I can tell you that they did have blocks they hung from the lifelines when lifting certain models. The blocks were covered with carpet to protect the hull. I don't know which models or the width of the Travelift.