Build a rack
I have a 7 meter that I use to photograph sea kayaks from. Sorry I don't have any photos, but will try to explain what I have done.
I have a custom built "A" frame that is nearly 7' tall. It is made out of 2" alluminium tubing and is welded to 1/2" by 4" wide by 36" long plate. This in turn is bolted into the deck at the front and rear with four stainless bolts each. There is also a piece that follows the transom, welded and gusseted to the bottom and then is bolted through the transom with 3 bolts on each of the port and starboard side. From the stern uprights to the front uprights there is a span of 36". The vertical uprights have been bent to so as to follow the contor of the tubes, then they are bent back toward one another leaving a gap of about 18". This gap is conected with the same 2" tubing but I have plates on it where my nav. lights, radio antena, gps antena and some day where radar will be mounted. Coming off of the uprights I have attached posts that come out horizontally. Each post is made of 1.5" stock and extends roughly 18". There are three sets of posts to each side allowing me to carry up to six sea kayaks very comfortably. In the stern I have reinforcement bars going from Port to Starboard - one horizontal between each upright and two going 45 degrees from its center to each top corner. On each side (Port and Starboard) I have one horizontal tube that goes bow to stern and has been placed 18" - 24" above each tube. All main conections are gusseted with 1/4" plate. The whole thing was powder coated with 2 layers for extra durability.
On all points where the kayaks touch I have put 1/4" foam. One side having adhesive for easy placement.
This rack is the second one I had built. The first resembled a car rack with 6' legs. It was made with 1" tubing and self destructed on it's maiden voyage in 6' high seas with in an hour. The one thing that I will recommend is to over build it. Use at least 2" stock! Even mounting this at the stern there is still alot of sheer. Make sure that the welder does not clean up the welds either. Grinding the welds to make them smooth will diminish their strength by at least 50%. The current rack has been out in bigger seas with a full load and has yet to have any problems at all. The only thing that is a pain is securing the kayaks. At this point I use cam staps since I can get them tight thus preventing the boats from moving on the rack. Perhaps another way is to use jam cleats. I may try that on the top mounted boats. Also no matter how sweet and strong your rack is, with a full load in seas you will have to slow down. The kayaks don't come cheap if we are talking about fiberglass and they will chafe or worse show stress fractures in the gel coat.
Hope this helps
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