Split Mold for Tumblehome?

[NomadAK]

I'm looking into a kevlar/carbon fiber layup of a pack canoe, something in the 13 foot range with around 24" width at the waterline and 27-28" max width. Looking at a lot of the designs out there, it seems that incorporating some tumblehome is a common (and probably best) practice among pack boats or other solo canoes.

My concern is around the mold-- I'll be laying up using a female fiberglass mold, created from a male wood/foam/drywall compound plug. I'm pretty inflexible on using a reusable mold, as I'm working on this project with a friend and we intend to lay up at least two boats, and I'd like the option of doing more down the road if need be. My big concern is around mold design for a boat with tumblehome-- am I right in assuming that a one piece mold will not suffice for this, as the boat would be locked in the mold after curing? If so, would a two piece mold, split down the keel line, be a better option?

We're looking to make this using a resin infusion process, which I know also adds complexity to having a split mold. Has anyone done a build like this that can offer some advice? We're willing to take plenty of time and (within reason) money to make a proper set of molds to get this right, I just want to make sure I'm not missing anything important!

 

[BWCA66]

I would think you need a split mold but not the whole thing. Your hull will be flexible enough to pull it out of the mold even with your tumblehome if at least part of the mold is split. Here's a couple of pics of a mold split just at the end.

Greg

 

[Jim Dodd]

Greg has some good advise ! He's been there and done it ! And still doing it !

Just some of my own thoughts ! By building a male plug, and then a mold, for just two hulls, infused to boot, is a big undertaking, not to mention expense !!

Going through all that work and expense, you will want to be Positive what you are going to build will be worth it !!!

You need to paddle what you are going to build, to be sure it fits your requirements !! Really put it through the paces !

Test paddle all the canoes you can get your hands on, And when you find that one ! BUY IT !

I'm all for building and creating a canoe, but have learned very much the hard way, I could have bought several of the best hulls out there, with the money I've spent building !

Don't get me wrong, I wouldn't have had it any other way ! It's been a fun ride !

Now if you have ignored what I just said ? Build a stripper, use it for a male mold, and make two hulls from it !

Jim

 

[BWCA66]

A lot of female molds are made by first building a cedar strip, paddling it to make sure its what you want and then use it to build your mold.

 

[lowangle al]

Hey Nomad, I don't know anything about making molds but I have a Mohawk 13 solo that you can barrow if that helps.

 

[NomadAK]

Thanks for all the advice and suggestions! It sounds like a stripper may be in my future...

A bit of background on what we are looking for-- this started while I was helping a friend, who last summer I introduced to both kayaking and canoe tripping, to shop for a kayak for the coming season. As I listened to her intended paddling trips, desires, and requirements, I realized that an Adirondack pack boat would be a far better match. Unfortunately, I soon found that there aren't many Pack boat options up in AK. The closest option would have been a Wenonah Wee Lassie, but we've missed the order deadline for getting a boat up this summer. I've been wanting to build a boat for a while now, but been limited by garage space--something this friend has an excess of! She's fully on board with the build idea as well, and since bringing the idea up, a few others have expressed potential interest in a pack boat, so I think two hulls would be the bare minimum.

I think the strip built boat as a male mold makes a lot of sense, and furthermore gives us an entire extra boat! Using this method, are there any particular things I should be thinking of during the strip build that will help with making a mold (assuming it's what we want)? I'm also not 100% set on a boat with tumblehome, so if there are other opinions on the subject I'm open to hearing them.

lowangle, I definitely will take you up on that offer! Ice out can't come soon enough.

 

[lowangle al]

You can borrow it anytime, but I meant that you could use it now if you needed to get some measurement from to build your forms. I may also be selling it and a bunch of other boats this summer as I am possibly moving soon.

 

[Jim Dodd]

If a Wee Lassie is on the order you are wanting ? It has no tumblehome to deal with. Easier to built with less time and expense.
Designed for a Double bladed paddle. The variety I've built track great, and are very stable.
Mac McCarthy has a Wee Lassie II, that I've built, and like !
http://www.feathercanoes.com/

Jim

 

[NomadAK]

You can borrow it anytime, but I meant that you could use it now if you needed to get some measurement from to build your forms. I may also be selling it and a bunch of other boats this summer as I am possibly moving soon.

Much appreciated! I'm out of town for a bit but will PM you.

If a Wee Lassie is on the order you are wanting ? It has no tumblehome to deal with. Easier to built with less time and expense.
Designed for a Double bladed paddle. The variety I've built track great, and are very stable.
Mac McCarthy has a Wee Lassie II, that I've built, and like !
http://www.feathercanoes.com/

Wee Lassie is not *quite* what I'm looking for, but it was the closest boat that I found with an Alaska dealer network. Overall, the closest boat I'm seeing is the Swift Keewaydin 14, or potentially their Pack Adirondack 13.6 if we decide for something a little smaller and with less rocker. That being said, if eliminating the tumblehome saves significant time, expense, and experience needed, then we may look at other options. My biggest concern is around gunwale width- I'd prefer to keep it relatively narrow (<27") for easy and efficient double-ended paddling.

 

[BWCA66]

If you build a stripper that you might use to make a mold don't be like Jim and epoxy your gunnels on because you will want to take at least the outer ones off to make a mold! Love Jim Dodds boats though!

 

[yellowcanoe]

Swift uses shouldered tumblehome to deflect broadside waves down
Very useful on larger lakes. The wide point is about two inches below the rail
Other tumblehomes have width down low which allows waves to tide up over and into your lap
Infusion means you probably got money
I have a boat made from a split mold
Not many were made the mold broke
Joe Moore at Placid Boatworks has been using a standard split in half mold and vacuum infusion since about 2000

 

[Jim Dodd]

If you build a stripper that you might use to make a mold don't be like Jim and epoxy your gunnels on because you will want to take at least the outer ones off to make a mold! Love Jim Dodds boats though!

Good Point Greg !

I can only afford to build one extra, so the stripper, used for the mold, is Before I trim it !

Thanks Greg !

Jim