Keel/keelsons Question

D

Dave Archer

New member
I have almost completed my male plug for a one-off fiberglass construction. The boat plug is 15' long with a 10% deadrise. If I add a keel to the plug, it will leave a recessed keel in the inside that I can stiffen, which will provide a long stiffener. I understand that the keelsons protect the hull, especially when aluminum strips are added. Here are my questions. Again, this is a solid fiberglass boat without a marine plywood core.

Do the three keelsons, as in the Scaup, provide better turning?

Is one inch by 1/2 inch sufficient?

Should I add them after the hull is completed? This makes glassing the hull much easier and less concern over blisters.

Or, should I add them to the plug so that I have the opportunity of reinforcing each keelson with additional mat inside? The disadvantage here is that now I will not be so eager to add screws to an aluminum strip on the outside.

So, I am torn between adding the keelsons later, which would allow a raised surface to screw down an aluminum strip, or building the keelsons into the plug so I have three long slots to reinforce when I work on the inside of the hull. Does anyone have experience with this dilemma?

View attachment bow.jpg
 
To simplify construction add your kelsons later. They will act as stiffeners. It will be much easier to glass with out them on the plug.
 
Thank you. Although it seems like the obvious, I was really struggling with how to go about this. Yes, it will be a lot easier adding them later. I just wish I didn't have to wait for spring to do the lay up!
 
Dave,
any time you add to a mold you have to be darn sure you dont lock the part to the mold with the shape of the addition.

I think you will be fine fabbin the part after(even in place and tehn attaching it to the hull.

Are you going to use any core to stiffen the hull?

Bob
 
I only have book knowledge of core materials such as C-Flex or sandwich core materials. This is a small budget project, although I do worry about hull strength. When I get to the inside of the hull, I will add bulkheads and ribs. I may add some hull stiffeners inside from end to end. I would notch the ribs and bulkheads. When I built my scull boat, I had a full-length keel as part of the mold. When I flipped it over, I cut a one-by-one inch strip of Trex plastic decking down the keel slot. Then I glassed around it and filled it. The resin really adheres to Trex. I then was able to attach an aluminum strip to the outside keel. Trex is heavy, but I am thinking of using it as a hull stiffner and maybe as ribs. Again, I would make long 1"x1" strips full length.

I ran into a material that was a light-weight 3/4" sheet material out of a resin made material. It was light! The guy I bought it from was a Bob Hayden, a scull boat maker. I have been unable to locate him to find out the name of this transom material. I found his son, but he did not know the name of the material. Bob sold it to me for a scull boat transom. I have looked all over the Internet. It is a cream color material, and I assume it was sold as a 4'x8' sheet. Does anyone know the name of this material?
 
I have a sample still. This material is solid, although my guess is that the material has air cells added in the manufacturing process. I followed the link, but as yet I can not find it. All of these materials are so expensive. I'll keep looking because I have a sample from Bob Hayden. He used it in his scull boat transoms so when you cut the hole for the boot, you didn't have to worry about wood rot.
 
Dave, I agree.... Coosa is a great product, rot resistant and good strength to weight ratio(light and strong).
For the keelsons it would be simple to add a profiled peice. I'd add a vee shape as it would be easy to glass over depending on the weight of the glass. Staggered layers of light glass would be easy to fair in to the hull, and if the core is polyester putty made with cabosil fitted to a mold teporarily hot glued into place then abrading through would not be an issue. Cutting a 3/4 inch board on a 45 and putting duct tape on the side to be wetted, and then cutting a spreader to the opposite side also a 45 then fill hole under the 3/4 board and and drag down the legth of the keelson would make a vee shaped profile. The board can be changed to taper from 3/4 to 0 or resawn to make it more easily bent. Hope this makes some sense. If you'd like pm me and I can call you to discuss more clearly.

By the way I used to live in Livingston, MT for three years. Lots of good waterfowling. Where do you use the scull boat out there. I've got a mmbgf and use it a bit here in s.c

Frank
Middletonboatworks.net
 
Scott, Frank, thank you so much for your imput. Yes, the Coosa Composites are impressive. I found a source in Seattle. I will use the material for bulkheads and knees, as I just don't want to use plywood, even though plywood would outlast the number of years that I have left. Shipping is expensive, however. As I have a sensitivity to epoxy, I will just use polyester resin.

OK- I now know what I will do regarding the keelsons. Again, I thank all of you for taking the time to help me, and I especially want to thank Eric Patterson for starting this wonderful site and sharing his boat project.

Frank, I use my scull boat up on the Flathead Lake, although my sculling prowess is greatly diminished by failed shoulder surgeries
 
Dave, I'm 40 and after a good day of it I'm feeling it. I seperated my shoulder at 19 and will probably be in your boat(pun intended) in a few years. Take care, Frank
 
Dave,
If you need to contact Bob Hayden, go to the classified and he's right near the top. Click on his name and it will take you to his profile and you can PM him. I was in contact with him earlier today.
Give him a shout if you need.
Lou
 
If you are not too sure about your keel and keelsons, add them later. If you are pretty sure of your design add them to the plug and make them a part of the mold. The convoloutions of the keel and keelsons will make the hull bottom much stiffer. Much like corrogated metal roofing as opposed to plain flat sheetmetal, Use divinycell or corecell for bulkheads it is a fraction of the weight of coosa board and much tougher under stress. Rich.
 
Allow me to digress for a moment on a small common (or uncommon) courtesy.
When responding to a post...respond to the post that you are providing an answer to....NOT to the last post in the thread. The post/person you are clicking "post reply" to.... is notified that you are responding to THEIR post.
I'm in the shop working and if I hear the "ding"...you've got email and a reply to your post....I look at the post...and, often, it's merely somebody responding to the thread....and not a notification to me at all.

So...reply to the post you are answering, not merely to the last post in the thread.
Thanks,
Lou
 
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