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Thread: Using a Tidal Grid

  1. #1
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    Default Using a Tidal Grid

    When launching my Ingrid Julia after nearly two decades on the hard, I expected a bit of leaking while the hull took up. After two weeks I was still pumping mightily, but it was all due to one 4 ft section of just one seam. Time for a quick service. The job didn't warrant a full haul out, so I elected to use a tidal grid.

    There isn't much online about them, so here is my experience.

    Poulsbo has one of the last tidal grids in Puget Sound, and it cost me a whopping $25 to use it for one tide cycle. The worst part is that I had to wake up at 04:00 to get on at high tide.

    The first job in using a tidal grid is to survey the structure at low tide and decide how you will be supported. I compared a photo of my boat before launching with the grid and determined where to position the hull for optimal support. If you have the center of gravity out beyond the forward support, the whole boat will fall nose down and may flood before floating off. Too far aft and you risk damaging the rudder.


    Luckily I have a 10,000 lb iron keel stretching the full length of the bottom, which makes a massively strong beam to land on. This (older) photo shows the keel. I wouldn't do this on a fin keel, though it has been done.







    After positioning the boat in the correct place at high tide, I arranged the fenders and lashed both masts securely to pilings. My great fear was falling over away from the pilings. A halyard was ran to the dock to give the boat a slight list inward while the tide went out.

    Due to the curve of the hull and my positioning, the hull only touched at one piling. I used three fenders in the area, with a 2x8 spanning them. The board is made off to the boat at deck level. The forces on the board can be substantial.



    Now hurry up and wait for it to start bumping on the bottom. You want to make sure everything is just right as it touches, because if things start to go wrong they are only going to get much worse and there is nothing you can do. I monitored the lashings to the dock, the fenders, and the list inducing halyard.



    Eventually the boat settled, slightly bow down and leaning against the pilings.



    Unfortunately on this summer weekend, the Saturday market ends right at the tidal grid. So my wife ran interference on the tourists, while I got to work reefing out the seam. Apparently this grid is very rarely used, and we were quite the spectacle.

    As you can see, this grid is sized for some seriously large vessels.


  2. #2
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    Default Re: Using a Tidal Grid

    I think I've been there. Can't recall for sure but my memory box seems to have a smaller vessel than yours sitting on the grid when I was there. she's looking great. Looking forward to hearing more about what you're doing with her.
    Cheers,
    Daniel
    If one advances confidently in the direction of his dreams, and endeavors to live the life which he has imagined, he will meet with a success unexpected in common hours.
    -Henry David Thoreau-

  3. #3
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    Default Re: Using a Tidal Grid

    I reefed out the seam compound and probed the cotton a bit. It was very loose in the area, and one small part seemed to have little or no cotton at all. This seam is where one of the supports for the transport trailer was, I wonder if it shifted things slightly in transit.

    I reseated the caulking and knocked in another small amount on top for good measure.



    A bit of seam compound on that, I used some modern stuff from a tube due to the wet seam and need to cure under water. Good as new.



    As the hull dried in the sun, a few patches that stayed wet showed where other small weeps were, I took the opportunity to get a bit more seam compound on those as well. Be careful! It is seriously slippery down there. Whatever you are wearing will smell like the bottom of a harbor before you are through.





    Yes, we have big tidal ranges here.




    That's really all there is to it. Careful planning, positioning, use of fenders, and making sure you settle the right direction. It helps to have a grid that has the barnacles cleaned off of the business surface like this one. Temporary blocking could be fastened down on the previous low tide if needed.

    It is worth noting that scraping the bottom or applying paint is strictly forbidden on the grid for obvious reasons. I collected all the seam compound I reefed out for disposal.

    Soon enough the tide came back and we floated free, and the pumps stayed silent!

  4. #4
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    Default

    Mission accomplished! Thanks for the tutorial.


    Sent from my iPhone using Tapatalk
    Alex

    "A man who is not afraid of the sea will soon be drowned, for he will be going out on a day he shouldn't. We do be afraid of the sea, and we only be drowned now and again" Aran Islands Fisherman

  5. #5
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    Default Re: Using a Tidal Grid

    I didn't know there were any grids still in use. I've seen that one there but thought it was abandoned. Not sure I'm brave enough to try it although it seems you thought it out pretty well. I have a friend who has one of the very early wooden Ingrids on the North end of Texada Island. He's had it many years. Named "Gretchen", he has her very traditionally rigged, Manila, dead eyes, gaff, etc.

  6. #6
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    Default Re: Using a Tidal Grid

    Thanks for this. I can see how things could get a bit tense as the water goes out...
    "If it ain't broke, you're not trying." - Red Green

  7. #7
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    Default Re: Using a Tidal Grid

    Quote Originally Posted by ron ll View Post
    I have a friend who has one of the very early wooden Ingrids on the North end of Texada Island. He's had it many years. Named "Gretchen", he has her very traditionally rigged, Manila, dead eyes, gaff, etc.
    Cool, another one to add to the list. There are a surprising number out there, not including the many fiberglass and cement versions.

  8. #8
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    Default Re: Using a Tidal Grid

    Great info - thanks! I had no idea there were any grids anywhere near Seattle. I'm with Ron though. I doubt I'm brave enough to use one although I suspect it's one of those maritime skills that's worth learning and preserving, much like kedging. Not needed often, but when you do need it, you *really* need it.
    - Chris

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    Life is short. Go boating now!

  9. #9
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    Default Re: Using a Tidal Grid

    Very educational.
    Quote Originally Posted by James McMullen View Post
    Yeadon is right, of course.

  10. #10
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    Default Re: Using a Tidal Grid

    Good job, we do it all the time with fin keels. Its something you get just used to and now every quiet wharf piling or tidal bay with a tree looks like a grid

    With your boat it might be worthwhile make some beaching legs if youre not so keen on diving to keep it clean.
    whatever rocks your boat

  11. #11
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    Default Re: Using a Tidal Grid

    Good stuff! It would be great to have that available here in the N.E. (we have only about 3-4 foot tides here though.) I've often though about and wondered if I'd have the courage to try careening my boat on the beach for some quick work.

  12. #12
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    Default Re: Using a Tidal Grid

    A calm day and a gently sloping sandy beach and I see no reason why I wouldn't try it. I'd lean toward beaching legs as well with that vessel. (no pun intended on the leaning part)
    If one advances confidently in the direction of his dreams, and endeavors to live the life which he has imagined, he will meet with a success unexpected in common hours.
    -Henry David Thoreau-

  13. #13
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    Default Re: Using a Tidal Grid

    Great post, J.
    Julia is a beauty. Can you tell us more about the 20 years on the hard? Is she new to you?

  14. #14
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    Default Re: Using a Tidal Grid

    This guy in Olympia did not plan so well.

    I met your honey and boat briefly in PT, very nice!

  15. #15
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    Default Re: Using a Tidal Grid

    He didn't plan so well but Oh was he lucky she wasn't sitting a few inches to port of where she is or she'd have likely rolled right over and pierced her bilges.
    If one advances confidently in the direction of his dreams, and endeavors to live the life which he has imagined, he will meet with a success unexpected in common hours.
    -Henry David Thoreau-

  16. #16
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    Default Re: Using a Tidal Grid

    There are couple of grids here free for the use as long as you plan ahead and let the managers (a fishermen's coop and a town landing) know. Our boat is MUCH smaller and less worrisome to 'settle in'. I love 'em as long as the footing isn't too slippery or deep mud.

    "... and the great shroud of the sea rolled on as it rolled five thousand years ago."

  17. #17
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    Default Re: Using a Tidal Grid

    I saw the gird a few weeks ago in Poulsbo, but, like Ron, I thought it was abandoned.

    Years ago I used to beach my schooner-rigged surf boat to paint the bottom.
    Elect a clown expect a circus

  18. #18
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    Default Re: Using a Tidal Grid

    I've not been on a professional grid that gives working space from both sides and not on that much of a tide - three to four feet down here, nine or so on the Bay Side, so I generally need two tides to give her a shave and a haircut anyway. If the space by the dock has a mud bottom, I get out at low tide and weight some beams a balks. If sand and I'm lazy I just figure that my habit of running aground will keep the very bottom of the keel clean enough. I also from time to time just dry out on a sandbar, for which operation I like having legs lashed to the chainplates.

    I always settle the boat as nearly in perfect balance as I can so that the strain on the legs or either way on any pilings is minimized.

  19. #19
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    Default Re: Using a Tidal Grid

    There's one down in Garibaldi, on the Oregon coast that gets pretty regular use. I'd be suspect of trying it with a fin keel boat, though! The pic of the one in Olympia that fell over looks like one of the pilings may have failed.

  20. #20
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    Default Re: Using a Tidal Grid

    Quote Originally Posted by Ian McColgin View Post
    I like having legs lashed to the chainplates.

    I always settle the boat as nearly in perfect balance as I can so that the strain on the legs or either way on any pilings is minimized.
    Paul Gartside offers these plans for legs. I will make some... some day... when I've found suitable, thick, driftwood planks

    https://store.gartsideboats.com/coll...s-design-131-8
    "... and the great shroud of the sea rolled on as it rolled five thousand years ago."

  21. #21
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    Default Re: Using a Tidal Grid

    It would seem that with chainplate legs, a shallow beach and sufficient tidal range the grid would be superfluous Nice option! Again, with my fin keel I'd be nervous although I've seen it done.

  22. #22
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    Default Re: Using a Tidal Grid

    I made Goblin's out of knot free 4x4s that I relieved the corners, not fully down to 8-siding but close. At the top I reduced it further to allow a shoulder for the lashing to rest on. At the bottom I inserted a 1/2" steel rod to act as a spike to keep all from slipping. To keep the whole from sinking into a soft bottom I had a couple of foot and half or so 2x6 planks screwed into a cross with a hole through the center that was shaped to allow the butt of the leg nestle with enough taper out the bottom that the cross could find whatever level the bottom was and not be bound too normal to the spike. I would set the legs a little splayed so that the legs actually were clear of the gunnel and the boat essentially hung on the tackle from the leg top to a chainplate. The cross had a line from one end up to the leg a couple of feet.

    To set the thing I'd hold the leg over the side, spear the hole, and then push down into place. To remove, just pull up. If the cross was sunk in some gunk, the line's pull on just one end would pry it up.

    I think that something a bit more like the basket on a ski pole would be both more elegant and more easily stowed.

    Many in Great Britain have legs that attach to a fixed bolt and a guyed fore and aft down low, allowing the boat to go through multiple tides unattended. The legs I use are suitable to one tide only and will float out of position when the flood lifts the boat.

    You can either calculate the leaning force, assuming you know not only the basic dimensions but also your metacentric, or you can do some controlled leaning experiments against some very robust pilings.

    Lots of room for improvisation here.

    G'luck

  23. #23
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    Default Re: Using a Tidal Grid

    Cool thread, the likes of which brought me here in the first place. Thanks.

    Kevin
    There are two kinds of boaters: those who have run aground, and those who lie about it.

  24. #24
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    Default Re: Using a Tidal Grid

    Excellent description of using a grid!

    We used to call the process "beach 'n bleach", back in Maine, when giving the bottom a scrub. Good for getting scraps of pot warp out of your propellor, too, after the spring tides had floated the usual mess of junk off the beach. With a 12-14' tidal range, pretty much any dock or piling (in good repair) that had good ground next to it was fair game. I've really missed having the option here in WA.

    Seven years in Poulsbo and I didn't know that grid was still useable. Nuts! I need to find that one in Oly, now that I'm here.

    I've long been contemplating how to make Bucephalus's sweeps do double-duty as beaching legs. With a 3'4" draft and 9'6" sweeps, it seems like it ought to be possible if I built "splatchers" for the bottom, as Iain describes.

    Alex

  25. #25
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    Default Re: Using a Tidal Grid

    Gartside's beaching legs have the option of the bolt-on type if wanted.

    Those knots of lobsterpot warp cut off your props? Make excellent Christmas tree ornaments or decorations for wreaths: "Humility crowns"
    "... and the great shroud of the sea rolled on as it rolled five thousand years ago."

  26. #26
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    Default Re: Using a Tidal Grid

    Quote Originally Posted by StevenBauer View Post
    Great post, J.
    Julia is a beauty. Can you tell us more about the 20 years on the hard? Is she new to you?
    New boat to me, a bit of a barn find. Restored 20 years ago and then never re-launched.

    Quote Originally Posted by wizbang 13 View Post
    I met your honey and boat briefly in PT, very nice!
    Sorry I missed you, though I did see you whizzing around during the sail-by.

  27. #27
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    Default Re: Using a Tidal Grid

    Tidal Grids are great. We used to use them for all the bottom maintenance....bottom scrubbing, partial re-caulking, scraping, painting with anti-fouling,changing through-hulls, even the occasional bit of planking, probably only short lengths because you have to get things buttoned up in ~12 hours maximum. Today you scrape the bottom and all the sealife and about half the old bottom anti-fouling falls to the bottom of the dock....it needs to be removed. We cannot just leave it there like we did in years/decades past.

    A proper tidal grid today should have a concrete pad so all the old bottom paint can be collected and properly disposed of. Incidentally this also makes a better working surface for the people working on the bottom as well. I know of several of these....notably two in Comox B.C.

    Most anti-fouling needs more time to properly set than is allowed in one turn of the tide, so you are left with less than high performers.

    I really appreciate the job you did on the grid...perfect use all around thanks for sharing.

    FWIW I take ground regularly...intentionally....al little bottom scrub....scrub the waterline....whatever....twice or three times a year.

    it is difficult to get under Whimbrel for a good scrubbing, because the ballast keel is very shallow and access is not that easy.

  28. #28
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    Default Re: Using a Tidal Grid

    J.Madison wrote: "...if things start to go wrong they are only going to get much worse and there is nothing you can do."
    And that's why boating is such a relaxing pastime.

    Nice write-up.

    Chip

  29. #29
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    Default Re: Using a Tidal Grid

    Quote Originally Posted by gilberj View Post
    Tidal Grids are great. We used to use them for all the bottom maintenance....bottom scrubbing, partial re-caulking, scraping, painting with anti-fouling,changing through-hulls, even the occasional bit of planking, probably only short lengths because you have to get things buttoned up in ~12 hours maximum. ....
    The idea of opening up the bottom (as in replacing a plank or through-hull) with an "I'm screwed if I don't get this done" deadline would make me very, very nervous. Methinks you are a braver man than I!
    "If it ain't broke, you're not trying." - Red Green

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