I don't think it was the fault of the hollow concrete block.
I have been using the same blocks for the past 15 years with no problems.
The picture shows the blocks on the ground with no footings. If the soil under the left block setteled a bit that could cause the block to crack!

 

I agree! They build buildings with the things.
The block probably cracked because it was used improperly.

 

I'm in agreement with AmberRay. We have been using cinder blocks at our club for the last 15-20 years without a problem. We use wood on top of the cinder blocks so the boat does not come in contact with the hull.

Glenn

 

i would hope that the boat is always in contact with the hull!!

 

probably wouldn't have cracked if they had put some wood over the block to distribute the weight off off a single point.

amberray,
how does your boat get up on the deck?

 

probably wouldn't have cracked if they had put some wood over the block to distribute the weight off off a single point.

amberray,
how does your boat get up on the deck?

Wish2fish,
A barge with a crane comes down the canal in the fall to lift me out and returns in the spring to put me in. Each haul is
$220.00. Alot less expensive than keeping it a the marina!

 

Are solid wood blocks that hard to come by? I've only ever used solid wood keel blocks and so does my yard. Pressure treated wood will last a long time. I'd be afraid of concrete blocks either shattering or damaging the hull.
JMHO

 

My last marina used wood blocks. Not PT. Just big old hunks of wood. Not sure where you can get those nowadays. Our new place uses concrete blocks but they lay wood at the contact points along the keel. Both marinas use boat stands laterally under the chines and aft. I would prefer wood b/c of it's elasticity - concrete has no ability to flex.

 

Concrete blocks and cinder blocks are not the same thing. Concrete blocks are significantly heavier, denser and rated to carry much more weight than cinder blocks, with far greater form strength. Concrete blocks would be a much better choice for blocking large boat hulls than cinder blocks, which are much more prone to crack under when weight is concentrated on a small surface section of the block.

 

I think the first problem might be is that boat looks like its stored at Service 1.

 

I continue to be amazed at the short cuts northern boat yards use for storage. It is a wonder we don't see annual posts about boat damage due to concrete or cinder blocks, not enough blocks, inadequate number of jack stands, boats falling over, etc.

Here are a couple of photos from a Sea Ray dealer and how a boat should be blocked for service:

 

Like all un-reinforced concrete, a blocks strength is in compression. The OP’s boat could be balanced on one 8” hollow concrete block if the block was on a proper base, meaning it has to be supported uniformly, with the total load also spread uniformly on the top surface of the block. This certainly would not be good for the boat but the block could do it.
Having said that a concrete block is to easy to misuse in a boat blocking application. They also get thrown around and abused(nicked and chipped) when not under a boat. Not a good thing for the block. I would suggest not using concrete blocks for supporting a boat. One of the problems with boat cribbing is storage during the off season. Concrete blocks can be stacked up neatly for example taking up less space than boat cradles. I can see why some yards use them. If I stored in a boat yard that used concrete blocks I would furnish them with proper wood blocking and insist that they use it on my boat.

 

If I stored in a boat yard that used concrete blocks I would furnish them with proper wood blocking and insist that they use it on my boat.

Fine. Which brings up the question someone asked before. Where can you got wood blocks that size.

I'm guessing that here in the north there are a lot more boats blocked at a given time (ie: winter) than in the south, where a boat is blocked for a week + at a time. Not justifying cutting corners, but it's easy to see why they use concrete up here. I'd consider wood if I knew where to get it. Also, not sure about "legal responsibility" of the yard if something happens to my boat which was blocked on my wood. Sounds like an escape clause for the yard.

How about a bean bag? Think that'd work??

 

Fine. Which brings up the question someone asked before. Where can you got wood blocks that size.
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Ron;

Really shouldn't be all that difficult. You're not going to find it at your local HD or Lowes, but any lumber yard should be able to special order it for you. Looks like 12" x 12"? The stuff is not common, but is used in post and beam construction and is available.

If you want, and can't locate any, feel free to pm me with what you're looking for and I'll check with my lumber suppliers.

 

Thanks. I could check at 84 lumber. They are definitely more hard-core than the home centers. Do you just cut it with a chain saw?

 

Wow, I had no idea that this thread would take the shape it has. Boat US's Seaworthy magazine a few years ago had an article about blocking in a winterization special. It recommended wood.

 

There were a couple of references here to ''short cuts taken in the north". Up here (in the "true north strong and free"), I've never even seen cinder or concrete block used for blocking a boat.

Here's a couple of pictures of our boat taken yesterday. This is even just temporary blocking for three days. It was hauled on Friday and is getting shifted into heated storage on Monday.

The large blocks were brand new - so you can get them somewhere. The keel had already sunk a quarter inch into the top 2 x 4 - lots of pressure on a small surface area.

I'm sure there are probably tolerance levels for different boat weights, but as I said, I've never even seen someone use cinder or concrete blocks in marinas around this area.

The other concern I would have using cinder block in the north is water intrusion and freezing. Any hairline crack or void will fill with water and it wouldn't take long for the block to split in two after a couple of repeated thawing and freezing cycles.

 

So you mean this isn't correct?

I have to move some foam around I guess?


http://cgi.ebay.com/ebaymotors/1989...emQQhashZitem4a9c03946fQQitemZ320445060207QQptZPowerQ5fMotorboats#ht_1075wt_775

 

That's funny!

We use large foam blocks (about 24"x24"x36") at our place. But, I'm guessing they're at least a "little" denser than the ones in that pic! :lol:

 

A barge with a crane comes down the canal in the fall to lift me out

AmberRay - that's great! What's the capacity of those barges? Do they have bigger ones too?

 

AmberRay - that's great! What's the capacity of those barges? Do they have bigger ones too?

I don't know who AmberRay uses, but the guy who is doing mine tells me that my 30' is about the biggest he can do. He aked me to make sure all the tanks were empty to lighten it up for him.

 

i dont think it's a north thing,i live in minnesota and my marina and all that i have seen around here,use big wood blocks.they look like they might be railroad ties cut in pieces. just my 2cents for what it's worth.:smt024

 

use big wood blocks.they look like they might be railroad ties cut in pieces.

Thats what my marina has also. :smt001