Unique Way of tying off to pilings in slip to keep boat centered during storm surge

[RonSurf]

I wanted to share something that came to mind at the begining of 2018 Hurricane Season. I wanted to create a way to tie off to pilings and keep the boat centered at all points during surge or extreme tidal swings.

Disclaimer: This is still experimental and could use some engineering calculations. This should only be used with the advice of a professional to be sure that it will keep your boat safe during storms. I will not be held responsible for any damage incurred for reasons of too many variables including boat sizes, dockline strengths, and surface area of structures above the waterline that create forces that challenge the physics of keeping a boat tied safely, which precludes having a one size fits all solution. This is why I recommend seeking a professional's advice before installing this in your boat slip.

The Set Up:

Tie a block using dockline and clove hitch to the top one foot of each piling in your slip.
Repeat the process at the lowest point at water level to the bottom of each piling.
Now, run a dockline from your starboard bow deck cleat to the top block on the piling and run it through, then down through the block on the same piling at water level, then back up to your bow cleat to be tied off. This forms a triangle.

Repeat the formation of triangles on all of the other pilings, beginning at each deck cleat, through the 2 blocks and back to the deck cleat on the boat.

Cool physics:

As long as your deck cleat height is between the upper and lower block on the piling, your boat will travel in a straight line up and down with tides. If it exceeds the top or bottom block, you will have to let out some line on the deck cleats. If a storm is arriving, tie off the boat to allow movement side to side to reach close to but not getting closer than a foot or so from pilings to allow for stretching of docklines during wind gusts or surge. Theoretically, the boat should stay centered even if the tide takes your boat above the tops of the pilings, but not too far above. Again, check with a dock neighbor with an engineering degree to be sure your boat will be safe.

Cost:

3 times as many docklines as you have now on your boat.
2 blocks per dockline that form each triangle. This means 16 blocks for 6 pilings, including 4 spring lines. With at least $30.00 per block, this will cost $480.00. Use the heaviest block that you can. Breaking Load of docklines are 7,000 to 10,000 lbs.
Some blocks range in the 3,300 to 5,000 lb. Range. 2 per triangle.
Adding the cost of docklines, at least $480 at $20.00 per dockline. This is for one dockline top and bottom of the piling to secure the blocks, and one to run from the boat, through the blocks and then return to deck cleat.
Not cheap: $960.00

I used this set up during the 2018 hurricane season. Winds here were up to 55 mph. I have not tested this in winds greater than that at this point. It gave me peace during winds and surge.

I enjoy this set up. It took two sleepless nights to finally come up with this, but now I don't worry about the dinghy on davitts hitting a piling, or rubbing against side pilings with tide changes.

I hope this works for you.

Ron
Biology Degree
Teacher of Science Certificate