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Old 04-29-2011, 04:36 AM   #1
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Winter blocking

I've got a question for all those who haul their boats for the winter: when positioning the blocks, most marinas (mine included) usually support*boats at three points;*two at the stern and one forward under the keel. This is an easy*setup since the boat will always settle securely onto the three points. To me, this*seems insufficient support and I've always had them place at least four extra stacks of blocks evenly spaced under the keel, which puts support directly under the engine weight (ours is a single), instead of it*hanging somewhat in the middle of*a support "triangle". *Am I just being anal here? I've read stories about engine/shaft re-alignments being required yearly due to hull "creep" during storage, and was wondering if anyone else has also lost sleep worrying about this.

Nick
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Old 04-29-2011, 05:09 AM   #2
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RE: Winter blocking

I would not allow my boat to be blocked like that.

3 poppets per side, at least 3 blocks under the keel.

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Old 04-29-2011, 05:40 AM   #3
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RE: Winter blocking

Ok, so have you ever had an alignment issue when the boat was placed back in the water? I agree multiple keel blocks are the way to go but they really do need to be accurately levelled to avoid overstress at a single point. Do you supervise the placement?

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Old 04-29-2011, 08:02 AM   #4
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RE: Winter blocking

"Ok, so have you ever had an alignment issue when the boat was placed back in the water"

Not that I have noticed, but I never run the boat other than idling from the launch well to a slip until the boat has been floating a couple of days min. In theory that is supposed to allow it to get back into it's natural state.

I have removed*the shaft on a few occasions with the boat out of the water and yes it appears out of alignment. I would expect that no matter how well it's blocked. The old Mainship 34 I had (1978) had a 103 inch long shaft and it would go way out on the hard even with the mid support bearing in place. I know I had checked alignment on that boat a few times in successive years after it was in the water for a few weeks and it stayed in alignment.
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Old 04-29-2011, 04:52 PM   #5
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RE: Winter blocking

Ours is blocked under the keel at two points forward and aft, and the three jackstands on each side. This arrangement works very well on our single 390. No alignment problems. I can turn the prop by hand.
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Old 04-29-2011, 06:12 PM   #6
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RE: Winter blocking

Thanks' guys, that's all good info. I hadn't realized that fibreglass hulls could*flex as much as they do when blocked. When viewing used 30ft express cruisers (Doral Prestancias) recently with a friend , all of them up on blocks, we noticed that on none of the boats would the head door open/close properly, but the owners all claimed the doors*worked just fine with the boat in the water.

John, I too have been able to spin the prop by hand each time I've had the boat blocked, and have had no vibration issues at launch. BTW, our 390 hull # is 383.......yours?

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Old 06-03-2011, 08:28 AM   #7
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RE: Winter blocking

One thing to be wary of blocking the keel is that w 2 blocks placed correctly the load is basically even. With 3 you could have 50% of the weight on the center block. My keel is not straight and when I put Willy on the tidal grid the first time almost ALL the weight was on the one grid beam in the center of the boat. Another was contacting further fwd but it was obvious it supported very little. I was quite nervous but all went well. Since then I've always tied 2 timbers to the grid beams at low tide and place the boat w the aft support close to the end of the keel. Got to go down and muck around in the mud and seaweed at 2am in whatever weather. Life is frequently imperfect. So yes Nick, the more the better but they need to be supporting equal weight or better put as much weight that is above the blocking.* Ask the crew how they achieve that. Three is usually enough but five would be really good. Also make sure the jack stands support very little weight as the only purpose for them is to keep the boat from falling over. If (for example) you over tightened a jack stand 10" to one side of a major bulkhead damage could result. But the jack stands need to be tight enough to keep the boat from moving around while you're walking around on it.
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