Advice sought on big guy kayak build

I'm thinking about building a kayak for myself and am just starting to look into it. My problem is I'm a big guy-and I worry if something built of red cedar would support me when standing up and if I used other wood or re enforced it somehow by making it thicker, etc, then it would be too heavy for me to carry and get all dinged up when using it if too heavy. Good is the strength on the bottom where I'd stand is needed-I am 6'5 and 425. I want to make a fairly long and wide one as I want to float high in the water and have good stability for fishing and I have a high center of gravity due to my height and size, so I flip over easily on the kayak I purchased (bought a 2 person one and moved seat to middle). But the one I bought has a very round hull and will never be stable enough for me to hook and fight a large fish here in Edgewater FL where big redfish and tarpon, sharks are fairly common. I am thinking of trying some home built sponsons or pontoons to stabilize my existing 14' 2 person conversion to get by until I can build the one I really want.

I would want an open cockpit design, not the hole you slide into, so I can have my gear and a cooler with me, much like a canoe but I want to not draw a lot of water as it is very shallow in many areas here, and I want good stability for rougher water or when moving around, setting hook, fighting and releasing fish.

Ideas from all are appreciated-thanks!

There's a magazine periodical called "Kayak Fish", there might be something of interest in there for you. I would also contact someone like CLC and talk to them about your needs. It's just a matter of designing in the correct flotation, initial and secondary stability. Sounds like a great, challenging project. I built a strip built 14' Canoe Yawl once from my own design and used 3/8" WRC for additional strength instead of the 1/4" typically used. I've also seen canoe builders use something with more inherent strength such as Spruce and/or add layers of glass/epoxy to specific areas to add strength where needed. Good luck,
Mac

Thanks Mac. Will look into it. Wont have time to work on it til next year so plenty of time to learn, I am in local woodworking guild here and one member builds kayaks and canoes all the time so I plan to pose many questions to her before starting

Layers of carbon fiber will keep it strong and light....and empty your wallet:)

What you want for stability is a LOW center of gravity (CG) and not a high one. As for open kayaks, I only know of one sit on top that you can build, and it is stitch and glue construction. http://www.guillemot-kayaks.com/guil...op_kayak_plans

As for Carbon Fiber, (CF) there is a myth that using CF makes the boat lighter. This is true only if you use a thinner layup of CF versus nylon or other fabric. CF is stronger and therefore requires a thinner layup to get the same strength- about 40% less thickness. Here is where folks go wrong- they swap 6 ounce cloth for 6 ounce CF. Since CF is lighter, a 6oz CF cloth will be as thick as 10oz nylon cloth. The weight comes from the resin, not the cloth, so in this case the person ends up with a layup almost twice as heavy as the 6oz standard cloth layup because of the resin it takes to fill the thicker weave. Going CF means you also need to go with a thinner cloth.

As for a cedar kayak being strong enough to hold you, a wood and glass laminate is much stronger than just glass. No need to worry. My expedition kayak has been literally thousands of ocean miles and survived a hurricane, as well as a few mishaps in the rock garden. No cracks yet.

If if you go with outriggers on a sit-in kayak or even on a canoe, go with the ones from Chesapeake Light Craft. They are excellent designed and easy to build. I design boats and if I wanted an outrigger for a kayak I would likely just go with theirs as it is time tested.

Being able to stand in a kayak - especially for a big guy - that's a pretty specialized requirement. And as Malcolm mentioned, there are very few designs for wood kit construction sit-on-top kayaks. Calculating righting moment at a considerable height to get stability factor is outside the realm of my experience. To my knowledge programs such as Kayak Foundry don't provide an option for calculating stability while standing either. Most of the manufactured boats (Jackson Big Red) that are touted as standable are quite wide at 36" or even more. Which is interesting considering that larger SUPs (like the CLC Kahalo) are just 29" wide. Were I to design a kayak to meet those criteria, I would plan on the possibility of failing in one or more of the desired criteria on the first pass and expect to build several versions getting to the perfect solution. So for instance, while the kayak might work for standing and fishing, the compromises such as weight and drag might make it exceptionally slow and heavy. Getting the perfect balance might take several tries.

Getting the optimized solution might be best left to those with a lot of experience and a commercial interest. Dave Harris from CLC might be a good chap to speak with. Likely there is a market out there for what you seek. Or Malcolm who designs SUPs. In some ways I see this boat as being a form of an SUP which supports sitting as well as standing.

A fellow named Ross Leidy (Blue Heron Kayaks) created a software program called Kayak Foundry (quite remarkable) that leverages stability and other algorithms to assist designers with optimizing their kayak design before building. The software is designed primarily for strip building. The software assists with the shaping, produces templates for the strip-built boat, and provides feedback on stability and drag (an over-simplification of course). There is a bit of a learning curve, but a forum of active supporters worldwide, and once you "get the hang of it" you can develop a hull design pretty quickly. It's a great deal of fun, and provides lots of feedback about design before committing to a build. While the software is not optimized per se for the sit-on-top design, I don't see any reason why you couldn't use it to design one. I used it to design a canoe where I was principally interested in the underwater shape, drag, centers of resistance, and frankly, the templates.

Keep us posted on your process! I have a brother-in-law for whom your design might work out perfectly.

I didn't like my tippy canoe so I made up a set of outriggers for it. Have you considered that approach?