Re: weight reduction tech

Posted by LeeG on Jun 4, 2005

ok,,you've got a kit with 6oz glass for hull/cockpit and 4oz for deck with 3" tape?

This is where you gotta be honest with yourself how important light weight is compared to long term cosmetic and structural durability.

And how important hatches and bulkheads are compared to two float bags.

And whether you want to stick with what came with the kit or venturing out into other types/weight glass cloth might bring another few pounds weight savings.

Before doing things that require new materials think of simply NOT using material where it's not structurally necessary.

Reduce epoxy goop use to the MINIMUM. That means use masking tape at chines and keel to limit fillet size. Don't bother with microballoons as filler,,just use less epoxy overall. After stitching use slightly thickened epoxy applied with syringe at seams,,when cured pull wires and lay masking tape just over the holes so fillets are about 1/2" wide.

Another way to significantly reduce epoxy use is to pre-seal the hull panels inside and out with a thin pre-coat of epoxy before assembling. If you aren't neat and this is a first time contruction you should use 2" clear packing tape all along the underside edge of the panel you are sealing so that any messy blobs of epoxy that are squeegeed off won't harden into big thick chunks. Using a roller to apply the epoxy will help reduce the slop that can occur with 'dribble and squeegee'. You'll waste some epoxy on the roller but it's better than wasting it on the wood. You roll on a light coat then gently squeegee any excess off. The tape will prevent what might have dribbled around from hardening on the other side. This will make wetting out the glass with minimal amounts of epoxy a lot easier later on.

Eliminate deck beams, bulkheads and hatches. Make temporary deck beams that are removed after the coaming stacks are cured. Eliminate deck glass with a couple patches of 6oz glass under the deck behind both cockpits. Use 6oz on the hull, 6oz in cockpit wrapping up the chines 1 1/2". Don't bother going up to the sheerclamps. Use cut 2" wide strips of 6oz to continue the chine joint foreward and aft of the cockpit cloth. Use a couple small blocks of wood in the ends with no more than a couple oz endpour in the bow and 4oz in the stern for rudder. Don't use push/pull rudder footbraces. If you and the other paddler are similar leg length then cut the Yakima rails in half and configure a hinged toe plate rudder control. 7" long rails with 4 positions should be plenty.

Not sure how long your race is but I'm assuming you could put all your gear into a couple dry bags between the two paddlers with float bags in the ends. Replacing bulkheads and hatches with float bags carries a BIG ASSUMPTION that the odds of capsize are close to zero or the conditions are such that a capsize isn't catastrophic,,if that's not the case then replace the 6mm bulkheads with 4mm okoume or get some cheap luann and glass it with 4oz. At this point if you're going for bulkheads and hatches there isn't much to be gained by elimating deck glass.

Basically you either really go for light weight and accept the compromises or spend all kinds of time for very little gains. I think if you put on a scale two 6mm bulkheads, hatches,hatchreinforcements,goop for contruction and hardware and on another scale you put two float bags there would be a significant weight difference. If you put on one scale the stock set-up and a lightened set-up it'll be lighter but in the big picture the gain would be marginal compared to the few hundred pounds of paddlers and boat.

Don't use 3" tape. Get a neat table for cutting cloth scraps in 2" wide strips with 48" ruler and pizza cutter style rotary knife. And use those 2" wide strips wherever needed. When putting down strips of cloth pre-wet the wood first then lay the cloth on so you aren't walking around with more of a fraying mess. The rotary cutter will make this a lot easier,,just don't do it with wet gloves.

Do all this work in 70+degree conditions so the epoxy is thin and you aren't fighting thick epoxy.

So using what came with the kit basically it's 6oz glass on exterior, 6oz glass on interior cockpit bottom (only go up 1 1/2" above the chine joint) and 2" wide strips continuing the interior chine joints with specific patches of cloth under deck behind both cockpits. No deck glass, no hatches, no bulkheads, no deck beams, no 3" tape (pick up 60' of wet 3' 9oz tape and see how much it weighs). That should be plenty durable and as light as possible with the stock kit.

If you want to make it even lighter but not have to get a 3mm deck and cost is a consideration Replace the exerior hull glass with 4oz glass with 2" strips of 4oz on the keel and chines for adequate bashability. Pre-glass the interior of the bottom panels with 4oz cloth when you do the pre-sealing before stitching. 4oz on the hull bottom will NOT protect the wood very well compared to 6oz but it'll all hold together. Basically anything that will make for a catastrophic failure on 4mm with 4oz on either side will be significant damage on 6oz on both sides.

The reason to eliminate push/pull rudder controls,,besides better bracing and boat control,,is to reduce the chances of rudder failure during a race where your entire leg strength can be applied to the rudder lines in an emercency. It's not necessary to have maximum leg press strength in order to move a little rudder a fraction of an inch. By removing that possibility you'll remove a lot of opportunities for swaged fittings and screws from breaking/pulling out and the consequences of having NO rudder when you really need a rudder.

In Response to: weight reduction tech by Brian Bills on Jun 1, 2005

Replies:

• Re: weight reduction tech by Dave on Jun 11, 2005