Bunks and Lift

Jim Puglise · Post by **Jim Puglise** » Tue Oct 09, 2007 3:51 pm

I have a 26S that I keep in a lift. The lift is nice because it keeps the boat out of the water and keeps the bottom clean. I can lower it into the water and be gone in about 3 minutes. That's the good news. My lift has two parallel bunks, similar to those in a trailer. The lift maintenance people say that the bunks should really be cut to the contour of the bottom for minimum stress on the boat. The current bunks are just straight 2 X 12 covered with carpet. Does anyone have any thoughts on how to get a good pattern of the bottom so that we can make bunks that fit?

Jim Puglise, Punta Gorda, FL

beene · Post by **beene** » Wed Oct 10, 2007 4:23 am

I would just copy the trailer design.

G

LOUIS B HOLUB · Post by **LOUIS B HOLUB** » Wed Oct 10, 2007 10:15 am

My preference would be the use of heavy duty nylon straps with your lift, if thats possible.

Lloyd Franks · Post by **Lloyd Franks** » Sun Oct 14, 2007 4:30 pm

Hi Jim:

Why not add bunks to the lift? Then tighten the supports where the boat comes to rest, just as you would if adjusting bunks on a trailer. The bunks would be parallel to the boat.

Lloyd

Steve K · Post by **Steve K** » Thu Oct 18, 2007 11:20 am

Hi Jim,
Don't know how you would do this with the boat over the water, but.........

You'll need a piece of cardboard that is about as long as the width of the boat, at the position of each bunk.

You'll also need a carpenter's compass (the drawing tool you use to make a perfect circle with, only much larger). You can make one of these with a couple of strips of wood, if you need to. Just take a couple of strips of wood around a foot to 18 inches long and bolt them together at one end, with a small nut and bolt. Then tape a pencil or magic marker to the opposite end of one of the wood strips.

(tricky part..... being you're over water):
Have a couple people hold the cardboard under the boat, so it touches the keel (strake, or lowest point of the hull that the bunk will touch... centerline). Each end of the cardboard should be equal distance from the hull at this point.
Adjust your compass to span the distance from the cardboard to the hull on one side. Now drag one side of the compass accross the bottom of the hull, while drawing the contour on the cardboard with the side you taped the marker to.

WA LA!!! By cutting the cardboard out along the mark, you now have an exact template of the contour you need.

This can now be transfered to wood to cut out a form fitting bunk.

The likely way you'll build this bunk would be cutting several copies of the contour out of marine plywood and stack them together.

I've thought of building contoured bunks for my trailer this way. However, I planned to fabricate them using fiberglass. Contoured bunks go a long way toward keeping the hull from developing flat spots.

Hope this was helpful.
SK (26D... "Three Sheets")

Jim Puglise · Post by **Jim Puglise** » Thu Oct 18, 2007 6:48 pm

Thanks to everyone for the responses. I got a start on it today doing it the hard way, which seems to be the only answer. The bunks run parallel to the keel and are 12 feet long. Currently, they are made from 2X12 X 12 feet. They are set on the edge, so that the boat is actually resting on the 2 inch edge of each bunk. The reason for this is to lift the boat above the lift due to the shape of the bottom. The lift people have advised me to replace them with a single 4X12X12 on each side. I first made up a 1/4 X 12 X 12 feet from 1/4 plywood. I was able to insert this between the mounting point for the bunks and the bottom of the boat. I then marked the plywood where the bottom contacted it and removed the plywood at that point. I then refitted the 1/4 ply, marked it again and removed some more. What I have is a template that I can use to cut the 2X12 so that it will match the bottom of the boat running from fore to aft. The bottom is not flat, so I can measure the angle at the point the hull will rest on the bunk and using the template to show me where to cut the 2X12, remove the correct amount of wood to provide a shape that will fit the bottom of the boat. I will carry this angle to the second 2X12 for that side and bolt the two of them together to provide a 4X12X12 for each side of the boat. It was no picnic getting the four 2X12X12s home and down to the water where I can work on it. Meither was it any fun repeatedly installing and reshaping the 1/4 inch template. I have the template to the point that it is about 80% fit and will finish tomorrow. I will finish the bunks and put the carpet on them then let the professionals install them into the lift.

On the other hand, maybe I should just go get a bottle of rum and mix up some limeaide and go soak in the pool.

BTW, still not sure I understand how a caprenter's compass works, but the idea sounds interesting.

Jim

Bawgy · Post by **Bawgy** » Thu Oct 18, 2007 7:07 pm

Raise the boat on the lift . Place a 2x12 or widest board you can fit under boat turned up on edge. Make a mark on board that corresponds with lift and boat . Take a level and touch bottom of boat near the end of 2x12. Take a measurement and if it is 10 inches then move toward the other end of 2x12 in 6 " increments marking the 2x12 at the 10 " mark. Connect the dots and cut the bunk on the line made by dot to dot line . There you have it . Just remember to park the boat in the same position each time in the lift

Jim Puglise · Post by **Jim Puglise** » Sat Oct 20, 2007 8:54 am

You're right. This would have been a much easier way than I did it and yielded the same results. I wish I had thought of it a week or so ago.

Thanks --

Jim

Bawgy wrote:Raise the boat on the lift . Place a 2x12 or widest board you can fit under boat turned up on edge. Make a mark on board that corresponds with lift and boat . Take a level and touch bottom of boat near the end of 2x12. Take a measurement and if it is 10 inches then move toward the other end of 2x12 in 6 " increments marking the 2x12 at the 10 " mark. Connect the dots and cut the bunk on the line made by dot to dot line . There you have it . Just remember to park the boat in the same position each time in the lift

R Rae · Post by **R Rae** » Wed Oct 24, 2007 9:32 pm

Right on Jim me lad !!

Get the bottle of rum first of all. Put away at least half of it, but don't spill any.

After that, I guarantee everything will look simple, straightforward.

Cheers, hic

Ron

PeteC · Post by **PeteC** » Wed Nov 07, 2007 10:00 am

Jim,

What was the maximum depth you had to cut out of the 2x12?

I ask because I am having to replace the lift cradle on my boatlift (rusted out). I currently have a bunk arrangement that mimics the trailer bunks. But I would like to go to bunks that are parallel to the boat centerline. I would like to use aluminum bunks if possible. I was hoping they would deflect to match the hull contour, but that may not be possible.

Thanks.

PeteC · Post by **PeteC** » Wed Nov 07, 2007 10:11 am

I looked in the Trailer mods section and found 3 trailers that had lengthwise bunks. see Tony Houk, Bert Neville and John (Clipster).

John (Clipster) picture showed the amount of bend in the bunk/hull shape. I assume then that a straight bunk would put a large amount of stress on the hull contact area.

macgregorsailors.com/cgi-bin/modtracker.pl?action=view&record=725

AndreEmmenegger · Post by **AndreEmmenegger** » Thu Nov 15, 2007 7:45 am

I keep a 26x on a lift also. What I did was match the contours of the trailor/boat where the cross pieces are for aprox 4 feet across or 2 feet off of centerline. I then ran a 2x12 lengthwise butted up to the crosspieces. The 2x12 are canted at an angle and match the contours of the boat. It really works well.

Andre

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Bunks and Lift

Bunks and Lift

Bunks and Lift

Bunks and Lift