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Boat on boat-lift positioning..

Old 04-06-2020, 05:25 PM
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Default Boat on boat-lift positioning..

Consulting the THT brain trust..

I’ve got a new to me boat and a brand new boat lift.

Although I think the boatlift and dock builder did an excellent job, his communication after the fact regarding the lift and its use has not been great.

He pretty much built it and then left and never came back..

When I contacted him to asked him if he needs to adjust it for my specific boat which I got after he built it, he told me he set it up generically for a 21 to 24 foot bay boat...which, to be fair is what I have..

That said, the bunks seem very narrowly spaced to me. I have walked around the top deck of the boat on the lift extensively, washing and tinkering and I have not felt it move, but I’d be kind of nervous with more than one person walking around in it, or more than one person on a single side of the deck..

It may be an unfounded fear, but regardless it makes me nervous how narrow they are spaced, under the hull..

Also, the bunks are of course significantly shorter than the boat and if I try to position the rear bunks to the rear of the transom, there is a ton of boat overhanging the front of the bunks..

Is that cause for concern?

Would any of you position the boat more towards the center of the lift or leave it as I have a positioned, with the end of the back bunks close to the transom?









Old 04-06-2020, 05:33 PM
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I would like to see the bunks moved out to the next strake , but the issue here is then the keel of the boat will rub on the I beams.
You can experiment to see how far apart you can move the bunks and not have the keel hit the beams.
Front to back positioning looks proper.Most of the weight is at the rear to center of the boat
Old 04-06-2020, 05:57 PM
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if you moved the bunks out, you could add 2x12s to clear the keel, you could also add longer 2x12s and fix both concerns
Old 04-06-2020, 06:00 PM
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Much appreciate the great replies gentlemen!
Old 04-06-2020, 06:20 PM
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It looks like they did a good job. For the weight distribution check the tension on the cables by pulling on them and try to place the boat where they are even. For the bunk spacing call the manufacture and have them send you the bunk spacing, although it looks about right. To avoid landing on the strakes center the boat by adjusting the pvc guides and balancing the on board weight (people) as you lift the boat. Good luck stay healthy and enjoy your new toy
Old 04-06-2020, 06:37 PM
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Originally Posted by proline34 View Post
It looks like they did a good job. For the weight distribution check the tension on the cables by pulling on them and try to place the boat where they are even. For the bunk spacing call the manufacture and have them send you the bunk spacing, although it looks about right. To avoid landing on the strakes center the boat by adjusting the pvc guides and balancing the on board weight (people) as you lift the boat. Good luck stay healthy and enjoy your new toy
Great reply! Much appreciate your thoughts!
Old 04-07-2020, 08:29 AM
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Recently, I went from a trailer to a lift. Bunks were not adjusted properly. Was easy to adjust.
My preference would be 3 things: transom support, widen the bunks out, and tilt the boat up some for drainage.
Looks like you can unbolt and raise the aluminum bunk braces up one hole. That will give you more clearance for the keel when you space out the bunks.
In your photo of the under side, My goal would be to space the bunks outboard of the "drain" or "water intake" ( whatever that is on the port side underbelly). Adjust the guides as needed.
Looks like you have enough bunk length to move the boat forward to get the bunks to near the end of the transom. This would be my priority, supporting the transom properly. You see this setup every dry storage marina. It's OK for no support forward of the center console.
Readjust either the forward or rear cable to obtain a rear downward angle for drainage.
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Old 04-09-2020, 06:33 PM
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Great reply and great food for thought .. Thanks!
Old 04-09-2020, 06:40 PM
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Your front and back positioning is almost perfect. I would actually say move the boat forward another 6", though you don't want that thru hull fitting sitting on the board

You might widen the boards by 4 inches or so at the stern, and 2 inches at the bow.

Check out "T chalks" as well.......they would go in place of your boards and the boat will settle perfectly every time
Old 04-10-2020, 05:24 AM
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I would look into getting taller aluminum bunks that have the rubber padded tops. I would totally get away from wood.




Old 04-10-2020, 06:17 AM
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Here are my T-Chalks....you can order them based on the deadrise of your hull.



Old 04-10-2020, 01:29 PM
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With regard to the T-Chalks what material are these made from?
my current set up is 4X10s with carpet but no bevel at all.
Old 04-10-2020, 01:39 PM
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Originally Posted by oasis04 View Post
With regard to the T-Chalks what material are these made from?
my current set up is 4X10s with carpet but no bevel at all.
I don't know as I did not manufacture them, am just an end user, but I would guess some mixture of ingredients like glue and sawdust?

They are incredibly dense, but not as heavy as they look. Call your boat local lift company and ask them about it.

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Old 04-10-2020, 05:00 PM
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RusticHills: the loading characteristics of a trailer (dynamic) and a boat lift (static) are different. The only thing in common is the boat. On a lift, the most important thing is weight distribution. Front and back of the lift need to be supporting the same amount of weight. Don't worry about where the bunks terminate in relationship to the the transon. Just make sure the boat weight is equally distributed. You can easy check by checking the tension on wires by pulling on them, or you can contact Robalo to find the exact location of the center of gravity - but again just check the wire tension. Balance loading is the key for the proper functioning and the safety of the boat. An unbalance lift can fail, and they often do. As to the bunk spacing -unlike a trailer - you want them narrow close to the bottom of V. If they are wide and further up the bottom like typically on a trailer, you will never get the boat side to side level . The boat will rock and sit on one side as your lifting it out of the water and you can run the risk of damaging hull penetration and starkes. Be safe and stay healthy
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Old 04-10-2020, 06:51 PM
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Many thanks for the great replies...
Old 04-11-2020, 04:56 AM
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I had a lift installed for my 21 Maratime skiff. The installer used 6 inch bunks as my boat had 11 degrees deadrise. I then ordered a new baot with 21 degree deadrise and realized I would need taller bunks to get the recomended 40 inch spread and keep the keel off the I beams. I went down to a local dock supply yard and bought true 2 inch wide x 12 beams. I covered them with black bunk carpet using spray adhesive and brass tacks and bolted them right into the 6 inch beams. At low tide coming back I have chipped the keel a couple times so I have also covered the beam edge with rubber in case I ever bump it again.
Old 04-11-2020, 08:25 AM
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I like to keep my lift and trailer's bunk spread equal to the stringer spacing of the boat. Keeps the boat fully supported all the time. Good luck, John
Old 04-11-2020, 08:30 AM
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If you keep the wood I would at least cover them with some of the "slide enhanced" carpet stuff.
Old 04-11-2020, 08:34 AM
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First off you shouldn’t be walking on the boat when it’s high on the lift. Especially with a lot of people. Lifts fail all the time. Try to get the boat closer to the water if you’re going to be doing a lot of moving around on there, such as cleaning on the boat.

another way to check the cable tension is to hit it with something and listen to the frequency of the sound. They should be similar if the weight is equally distributed.

Lastly you want the engines and transom supported as much as possible. Most of the boat can be hanging in the air as long as it’s the bow. Long bunks for big boats are usually only 10-20’ long.
Old 04-11-2020, 12:30 PM
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All around it looks good as is.

Don't be afraid to adjust the bunks yourself... I was scared to do it and called a lift guy and watched. I was ashamed afterward......

As has been mentioned, if you want to spread the bunks to the next strake you'll need to get bigger hunks of wood. I personally wouldn't bother. My last boat (a robalo) was in a marina on beds that close together and I preferred it because that's where the most glass is.

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