36 ft trifly cradle

rooferdave · Post by **rooferdave** » Sun Oct 24, 2010 7:21 am

here is an update on my cradle, made it out of 1/8 wall and 3/16 wall tube
going down to the club today to see how high my keel supports should be. The side supports (the cradle is currently upside down for paint) are 34" high and will have adjustable scew jacks fitted to the top of with wood and carpet.
http://i948.photobucket.com/albums/ad32 ... IM3680.jpg

http://i948.photobucket.com/albums/ad32 ... IM3682.jpg

http://i948.photobucket.com/albums/ad32 ... IM3683.jpg

http://i948.photobucket.com/albums/ad32 ... IM3684.jpg

captainmaniac · Post by **captainmaniac** » Sun Oct 24, 2010 10:45 am

13footbeam wrote:One more thing, your keel does a lot of the support work, your jacks are mainly to level and stabalize the boat on the cradle.

When I saw the your original picture I was going to comment that the design should be altered to provide a pad (or pads) to support the keel - which is what the weight really sits on .... then saw you did identify this in the later post. The challenge will be getting the right angle for the keel support, or building up sets of blocks on the cradle to the right heights, so you end up with the boat sitting at the right attitude (ie not too bow high or stern high). If you had the boat sitting over the cradle to take the measurements that would be easiest. Failing that, don't know if you have any measurements (or good pictures while you had it on stands in your shop that you can derive some measurements from) that you can use to get the blocking roughly right?

UPDATE : oops .. never mind... you posted re going down to take measurements for the keel supports while I was writing my post...

rooferdave · Post by **rooferdave** » Sun Nov 07, 2010 9:26 am

update

got the cradle built and just need a few minor adjustments and a bit more paint.

got more than a few comments on the paint job!

13footbeam · Post by **13footbeam** » Mon Nov 08, 2010 8:54 am

rooferdave, The cradle looks great if you are on ground that does not shift with the seasons, but it looks like it is a bit short and the main frame a bit too flexible, are you having to support the stern with seperate jacks? If so not good, this will be a problem because as you stated earlier, the ground shifts and if it does in your case it will put things out of wack which could affect the hull. Making one complete unit would eliminate the problem, but it would also need to be structurally more solid as well so no matter the points touching the ground surface it will stay true to the boats hull shape and not flex. Kind of like a fork lift, if one point comes off the ground, it does not flex. I think you could improve your design by adding some more beef but if I am seeing things corectly, you still have the issue of being too short, there is a lot of weight in the stern if your boat has the V-drive set up with engines and transmissions in the rear of the boat. Sorry to be a downer

Pat

rooferdave · Post by **rooferdave** » Mon Nov 08, 2010 10:04 am

thanks for the input Pat, greatly appreciated, size of cradle is dictated by the club storage. I modeld my cradle after another trifly in my club and was limited to keel length for position of cradle, for next year we will raise the back keel support to allow the boat to sit further back. The frame is 2x4 1/8 steel and the uprights are 2x2x3/16 steel and braces are going on next week, also new rear supports as it was a bit of a shock that I needed them but with a 600 tonne crane and 16 man crew I did not have a lot of time