stability solution floats
5 Comments Published by Adventures of Greg on Tuesday, October 16, 2007 at 5:35 PM.
Well, I have finally decided how I am going to gain my stability for moving about WiTHiN.
Here is a quick a review of the problem:
I decided after the roll over test, that stability in the prototype boat WiTHiN is just fine when I am seating in the cockpit. However, I do require additional stability for standing up through the top hatch, climbing in and out through the top hatch, and crawling on deck. We took a look at a number of options in the blog post. I decided to go with a ballast in a bulb on the end of a keel.
I calculated that I could take all of my internal ballast and add that to the keel as well, and calculated about 100 pounds, 4.5' below the bottom of the hull. I even went as far as drawing up plans for a stainless steel keel frame. Then when I was at the gym the other day, I picked up a 100 pound dumbbell to do my 20 single arm bicep curls with (ya, right!), and realized that there would be no way to properly secure this 100 pounds with a very long moment arm to my thin kayak hull!!!
After more thinking it just seemed dumb to have to lug around an extra 100 pound of weight just for the occasional time when I need to stand up. Especially for this prototype boat. I am trying to get WiTHiN ready for a mini-expedition in the Gulf Islands where I will spent a few days peddling and living aboard her to learn more about what it will be like to live in WiTHiN. I'll need to load and unload her by myself, and lugging this deep, heavy keel around is going to be a major pain.
So, I looked again at my retractable outrigger options and between me, Rick Willoughby and Richard Roake, we came up with the retractable slider-riggers.
These will be two outrigger arm that will slide in shell tubes that will be glassed right into the cockpit approximately behind my seat back. Each arm will be angled at about 30 degrees. When the floats are retracted, they rest against the sides of WiTHiN and will be molded to fit as if they were two short wings. When retracted, then should not cause much additional aero drag (head winds, not speed), and shouldn't effect WiTHiN's ability to right herself after a capsize. They should help stabilize her during sharp turns, as one of the buoyant 'wings' would dip into the water when she leans over during a turn.
When extended, they should provide enough buoyancy to allow me to stand up, climb in, out or walk on deck. They are not very hydrodynamic in the extended position in the water, but they are not meant for use while underway - at least not this prototype version of the outriggers.
I will be able to deploy the outriggers from inside WiTHiN by using handles through slots cut in the slider tubes behind my seat. If she were to capsize with the floats extended, I would be able to easily retract them from my upside down position inside the cockpit.
Here is how I am making them:
I modelled the outrigger shapes in my 3D application, then sliced each of up into 1" layers. I printed these flat slices out and tiled them together to create actual size patterns. I traced the patterns onto 1" thick Styrofoam and cut each slice out with an Exacto knife.
The 1" thick slices are stacked to form a stair-stepped float, glued together, then sanded smooth. The I will cover with glass and insert and glass in my aluminum outrigger arm tube.
Here is a quick a review of the problem:
I decided after the roll over test, that stability in the prototype boat WiTHiN is just fine when I am seating in the cockpit. However, I do require additional stability for standing up through the top hatch, climbing in and out through the top hatch, and crawling on deck. We took a look at a number of options in the blog post. I decided to go with a ballast in a bulb on the end of a keel.
I calculated that I could take all of my internal ballast and add that to the keel as well, and calculated about 100 pounds, 4.5' below the bottom of the hull. I even went as far as drawing up plans for a stainless steel keel frame. Then when I was at the gym the other day, I picked up a 100 pound dumbbell to do my 20 single arm bicep curls with (ya, right!), and realized that there would be no way to properly secure this 100 pounds with a very long moment arm to my thin kayak hull!!!
After more thinking it just seemed dumb to have to lug around an extra 100 pound of weight just for the occasional time when I need to stand up. Especially for this prototype boat. I am trying to get WiTHiN ready for a mini-expedition in the Gulf Islands where I will spent a few days peddling and living aboard her to learn more about what it will be like to live in WiTHiN. I'll need to load and unload her by myself, and lugging this deep, heavy keel around is going to be a major pain.
So, I looked again at my retractable outrigger options and between me, Rick Willoughby and Richard Roake, we came up with the retractable slider-riggers.
These will be two outrigger arm that will slide in shell tubes that will be glassed right into the cockpit approximately behind my seat back. Each arm will be angled at about 30 degrees. When the floats are retracted, they rest against the sides of WiTHiN and will be molded to fit as if they were two short wings. When retracted, then should not cause much additional aero drag (head winds, not speed), and shouldn't effect WiTHiN's ability to right herself after a capsize. They should help stabilize her during sharp turns, as one of the buoyant 'wings' would dip into the water when she leans over during a turn.
When extended, they should provide enough buoyancy to allow me to stand up, climb in, out or walk on deck. They are not very hydrodynamic in the extended position in the water, but they are not meant for use while underway - at least not this prototype version of the outriggers.
I will be able to deploy the outriggers from inside WiTHiN by using handles through slots cut in the slider tubes behind my seat. If she were to capsize with the floats extended, I would be able to easily retract them from my upside down position inside the cockpit.
Here is how I am making them:I modelled the outrigger shapes in my 3D application, then sliced each of up into 1" layers. I printed these flat slices out and tiled them together to create actual size patterns. I traced the patterns onto 1" thick Styrofoam and cut each slice out with an Exacto knife.
The 1" thick slices are stacked to form a stair-stepped float, glued together, then sanded smooth. The I will cover with glass and insert and glass in my aluminum outrigger arm tube.
Labels: boatbuilding
