Don't use cement blocks

Almost all the Marinas around here use some concrete blocks under the keel, however with a large block of wood as the top layer (which the keel rests on). All but one marina uses jackstands to hold the boat upright side to side.

Blocks in place of jackstands is CRAZY to me.

The keel on my boat is blocked in 3 different places along with 6 Jackstands total.

I highly doubt the owner blocked his own boat up, from the looks of the other boats they appear to be all blocked the same way in that picture.
 
The boat in the left of the picture looks like it is on blocks also. I have 2 friends that at at a YC in Toronto and they have haul out days. They rent a crane and all the boats are pulled over the weekend. It is up to the owner of the boat to block his own boat. A lot use concrete blocks it's an accident waiting to happen. We get a lot of snow and with the melting and the freezing the blocks can bust apart real easy.

Ken
 
My storage/service area near my lake uses jack stands and some blocks under the center keel. I happen to take this pic the other day when I was replace a piece of boot stripe. I wondered how hard it would be to make a cradle but now mine will rest on a new trailer so no more blocking for me! :)

fdc706d2.jpg
 
jg300da said:
Which way were those blocks set? Were the webs vertical or horizontal? I'm not advocating their use, just saying it makes a big difference.
Click to expand...

tobnpr said:
Not as much as you think. There was a lengthy thread about this subject awhile back.

No matter which way you stack them, they're still hollow. Unlike wood cribbing where the load is dispersed evenly across the total bottom area, you've got very significant point loads on a concrete block- the weight is borne solely by the three small webs. They're just not designed to take loads without reinforcing. For example, home built from CMU still needs a continuous concrete tie beam at the top just to take the load of the roof truss- and that's nothing compared to a 20,000 lb boat!
Click to expand...
I hope the world doesn't find about this. Actually a properly oriented block could hold the weight of several boats. It does make a difference. You don't see any kung fu guys busting them with their head when they're sitting the right way do you?
 
Cincy Aquaholic said:
My storage/service area near my lake uses jack stands and some blocks under the center keel. I happen to take this pic the other day when I was replace a piece of boot stripe. I wondered how hard it would be to make a cradle but now mine will rest on a new trailer so no more blocking for me! :)

fdc706d2.jpg
Click to expand...

Best would be to place wedges between the wood blocks. This would even the left/right load :wink:
 
I saw that boat today when I went to the marina

95c512af.jpg
 
Mike, Do you know the story to that ??.
As to what really happened to it.
 
Here's what I did. I like to keep the '3 point' solid and use the rest for basic support.
The 2 x 4's work well for that and I made some other stands from some scaffold feet.
I chose to put them on a the second strake rather than everything on the outside.
I'm going to pull the drives and check the alignment so I want it supported properly.
Picture1402.jpg


Picture1403.jpg


Picture1400.jpg


Picture1401.jpg
 
Last edited:
Isnt there a forum going on proper alignment techniques that states do it in the water after launch and a day or two for the hull to relax? Thats what my marina does.
 
JG
From the looks of the first block which is likely in the position it was placed, the hollows were up/down, not horizontal.

Panacea
That is exactly how boats at my previous marina blocks most boats smaller than around 30'. That marina is in Brick also but not the one your boat was at. problem is that boats with a single outdrive are blocked very high to leave the drive DOWN or to make for simple removal/replacement. Then they have to stack the blocks real high for support and the whole apparatus gets top heavy. The boat is typically pretty light and with a good blow, it's all over. I was working in my boat (dry weight 16500lbs) on Saturday, in the thick of the wind gusts, and the boat was shaking like a leaf so much I couldn't wait to get out of there. With that much movement, how can those precariously stacked blocks maintain position? It's a miracle more boats didn't topple over in those conditions.
 
rondds said:
JG
From the looks of the first block which is likely in the position it was placed, the hollows were up/down, not horizontal.
Click to expand...

I think you're right. The picture is kind of dark but I don't see any broken or crushed blocks. Looks like it may have blown or got knocked over.
 
Cincy Aquaholic said:
Want to see something crazy?? Look how my boat was blocked when I went to look at it for the first time just before I bought it. I can't believe the previous owners yard did them like this. Heck, there were 40 footers blocked the same way
Copy2ofP4170031.jpg
Click to expand...
`THAT!! is insane!!!
 
Wayne's World said:
I have 4 of these that hold my baby upright. :smt038
Stand-lg.jpg
Click to expand...

I use four of these as well; plus cement block on the keel just for a little support there. The tow guy put them in place when he delivered the boat stating it is good to support from the keel as well. So two jacks at the Stern, two jacks towards the bow--blocks on the keel.

Additionally, I chain the jacks together so they cannot move outward.

Lastly, for the stands, I seat them on 3/4" x 8" x 3' solid cedar two per stand.
 
For those of you who can't find a supply of wooden blocks and feel that concrete blocks are the only alternative, Magster's approach is a better alternative.

Early in my career I worked for a railroad. When railcars de-rail and flop around on the ground and can't be righted with a crane, they are lifted with manual jacks and blocking like Magster has done. This type of blocking is more than adequate to support a Sea Ray. Strength wise it is just as good as solid blocking, it just takes longer to set up.

The are a couple of cautions. Even though it looks like the 2x4 were spiked, this type of blocking is safest when the load is located in the center of the pile. Too much towards one side and the stack will collapse.

The other thing is that the real load bearing stacks should not be too much taller than the length of the boards. Each should be the same length. A square cross section would also provide more strength than a rectangle (4x4 rather than 2x4). It would also use the same amount of wood and be quicker to assemble as you would not need as many pieces to achieve the same height.

Magster's two outboard stern stacks would be shaky if they were carrying a significant load. But placed where they are, and with the stands in place, they really are more for stabilization than support. Nobody has mentioned it in this post, but it is the keel blocking that is supposed to support the boat. the stand just keep the boat from tipping over.

Henry
 
Henry Boyd said:
Nobody has mentioned it in this post, but it is the keel blocking that is supposed to support the boat. the stand just keep the boat from tipping over.
Click to expand...

This is what I have heard as well.

I have also heard the rule of thumb to have the blocks at the designated sling points for the boat. There was a thread about this a while back.
 
Henry Boyd said:
Nobody has mentioned it in this post, but it is the keel blocking that is supposed to support the boat. the stand just keep the boat from tipping over.
Henry
Click to expand...

Exactly.

ALL of the hull weight is to be on the keel blocking, fore and aft (three stacks on larger vessels, but that's harder to set up than two-point bearing).

The stands are set so that the pads are snug- but not bearing significant weight. Doing otherwise can deform or damage the hull.
 
You must log in or register to reply here.

Forum statistics

Threads
113,316
Messages
1,430,474
Members
61,174
Latest member
Bigram512
Back
Top