# Rebuilding my first skiff - looking for pointers



## Finn Maccumhail (Apr 9, 2010)

So I bought a Banana River skiff project hull from a fellow MicroSkiff poster who had it for sale here: http://www.microskiff.com/threads/banana-river-skiff-project-hull.39114/

This will my first time doing this and I'm looking for tips and ideas. My goal is to keep this baby clean for backwater fly fishing in the marsh- places my panga won't go. I'm thinking:

large open casting deck with maybe one hatch
open forward bulkhead
fuel forward
maybe put the battery forward
tiller steer
poling platform
get a grab bar/cooler rack fabbed up and screw into the cockpit floor
trim tabs
probably an open rear bulkhead w/ rear bench

I'm also considering hunting up an old pull-start tiller motor and having this with no battery or lights except for portable LED nav/anchor lights.

My primary questions are regarding materials. I'm less concerned with the budget than I am strength and weight of this boat. So can y'all school me on the pros/cons of using Coosa or a similar product for the deck, bulkheads, supports, transom support, etc? Since I want to have the rack screwed into the cockpit floor and have the fuel & battery forward I'm thinking of running some stringers w/ chase tubes for wiring and fuel line. Then surrounding that with buoyancy foam and putting a deck in.

If I'm understanding what I've found in researching the Coosa-type materials I could use minimal glass as the Coosa provides the structural strength and the glass is more for the finish and preventing any water absorption into the Coosa panels, right?


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## trekker (Sep 19, 2015)

Finn Maccumhail said:


> So I bought a Banana River skiff project hull from a fellow MicroSkiff poster who had it for sale here: http://www.microskiff.com/threads/banana-river-skiff-project-hull.39114/
> 
> This will my first time doing this and I'm looking for tips and ideas. My goal is to keep this baby clean for backwater fly fishing in the marsh- places my panga won't go. I'm thinking:
> 
> ...



Divinycell is a top notch material for these projects. Very light and suprisingly strong.


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## jboriol (Jan 2, 2010)

http://www.thehulltruth.com/boating-forum/244753-coosa-board-core-cell.html
This^

Super light build:








Penske transom and rod racks for deck support









3/4" Corecell decks 1/2" Corecell bulkheads.


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## Finn Maccumhail (Apr 9, 2010)

Thanks. I saw that and that was my guideline but not being a professional or all that familiar with the materials I wasn't sure how it would work. 

I'm gonna contact distributors and see if I can get my hands on some small samples to get a better idea of what I'm working with.


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## CurtisWright (May 9, 2012)

Coosa only for the transom. Divynal everywhere else. 


Also, consider portable fuel tanks. Built in are convenient, but is nice to be able to move the load from bow to stern in certain situations. For instance, making a run across open sketchy water, its nice to be able to shift all weight to the rear and keep the bow high.


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## Finn Maccumhail (Apr 9, 2010)

CurtisWright said:


> Coosa only for the transom. Divynal everywhere else.
> 
> 
> Also, consider portable fuel tanks. Built in are convenient, but is nice to be able to move the load from bow to stern in certain situations. For instance, making a run across open sketchy water, its nice to be able to shift all weight to the rear and keep the bow high.


I'll have trim tabs for those conditions.

How rigid are Divinycell & Corecell without being glassed? I know Coosa & Penske are very rigid and can be shaped with standard woodworking tools. Are Divinycell & Corecell similar? Obviously I'll be glassing things in, my neighbor across the street builds & glasses his own surfboards and he'll be helping but one thing you always hear is that 1st-timers almost always use too much glass and epoxy/resin so the boat comes out heavier than it should.


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## seapro17sv (Feb 3, 2015)

Don't stress about the potential added weight because of a less than perfect lay up. 1st, you have the help of an experienced glass man, and secondly, even if you were really sloppy and used too much resin, the added weight would only be a few pounds. You're buddy will give show you how it's done, the main issue being, too much resin makes a weaker lay up, not the opposite. More isn't always better. It's really quite easy, just be organized with your materials, and have a nice work station for mixing etc. Great looking boat you'll have for sure. Good luck with the build.


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## jboriol (Jan 2, 2010)

Curtis has some good points and knows his stuff. To add to that I will say that I was very aware of weight balance and made sure that I shifted the fuel tank back so that I could ensure that weight would be more amidship. You have to balance the ability to keep the bow up while underway first (so you don't take one over bow) and then level as possible float while poling. Tabs can't always help at low speeds and not at all while poling. Where most of your load will be in normal conditions should be thought through as you plan her out. Some things can be balanced out with moving tanks around, etc. but how you set up decks, storage, fuel and seating makes a big difference in the final performance.


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## CurtisWright (May 9, 2012)

Finn Maccumhail said:


> I'll have trim tabs for those conditions.
> 
> How rigid are Divinycell & Corecell without being glassed? I know Coosa & Penske are very rigid and can be shaped with standard woodworking tools. Are Divinycell & Corecell similar? Obviously I'll be glassing things in, my neighbor across the street builds & glasses his own surfboards and he'll be helping but one thing you always hear is that 1st-timers almost always use too much glass and epoxy/resin so the boat comes out heavier than it should.


You have to have glass on both sides of the divynal. For decks, 1 layer of 1708 on the bottom and two on the top is a good layup. You will need to build a deck mold or at least a flarge flat surface for laying up panels on. Divynal will not support the glass by its self.


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## Finn Maccumhail (Apr 9, 2010)

Thanks for the tips. I appreciate it.

I won't have a mold but have either a large table or just a big spot on the garage floor for building the layups.

Right now I've got to get the teak patio furniture I'm refinishing done and out of my garage so I can get started on this project. The wife asked when she could park in the garage again and I said, "Never, the garage is 100% mine from now on." I'll keep this skiff in the garage and the panga is in a storage unit 4 minutes from the house.


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## Centropristis (Jun 10, 2016)

What thickness coosa did you use on the transom? Is that one board across the full transom and one in the middle?


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## LWalker (Aug 20, 2013)

Nobody mentioned wood...my vote is 1/2" Okoume sealed on one side with one layer of 7-9oz glass on the other for abrasion. I am sure someone has done a weight comparison, but I am sure its not much in the grand scheme.


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## yobata (Jul 14, 2015)

LWalker said:


> Nobody mentioned wood...my vote is 1/2" Okoume sealed on one side with one layer of 7-9oz glass on the other for abrasion. I am sure someone has done a weight comparison, but I am sure its not much in the grand scheme.


x2!

I used 3/8" ply with 6oz on both sides for my decks


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## ceejkay (May 7, 2016)

I went back and forth on wood vs composites on my boat. in the end i went with 1/2" okoume. the weight difference was so minimal that it didnt matter. Now i would recommend you use epoxy resin over poly or vinylester resin. you will save the most weight with that. like yobata said he used 6oz on both sides, i had to use 1708 and matt on both sides. the mat helps with waterproofing but is added weight. epoxy will be waterproof on its own. (just need glass for the strength)

i dont know how the sponsons help over a traditional no sponson boat but these things are weight sensitive. with a 25hp on the back, battery and 6 gal tank in the stern my bow will stay high. to combat that i have a trolling motor and battery up front. ideally id like both batteries up front.


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## predacious (Sep 1, 2016)

wood is never a good choice - weight is about double,when using wood - example:
Penske/coosa board weighs 45% less that wood
wood requires epoxy - and that wood requires complete sealing,fail to seal,and you've got big problems quickly.

Penske/coosa board and divinycell - these require specific techniques,when fasteners are required - keep that in mind


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## Roninrus1 (Mar 9, 2016)

"Finn Maccumhail"!
I knew I'd seen that name somewhere!
I'm in Deer Park.  Probably 2-Cool or TX Kayaks?


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## Finn Maccumhail (Apr 9, 2010)

Roninrus1 said:


> "Finn Maccumhail"!
> I knew I'd seen that name somewhere!
> I'm in Deer Park. Probably 2-Cool or TX Kayaks?


That's me. Upper East Side a/k/a Kingwood/Humble/Atascocita/West Lake Houston area.


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## Boatdesigner (Dec 9, 2009)

In one of your earlier posts you mentioned the Coosa board provided the strength. That is completely opposite of the truth. The core just keeps the skins apart, they carry all of the load. When you calculate a foam/balsa cored laminate, you don't include the strength of the core, only it's thickness. If you are going with glass decks, I'd use Divinycell or Corecell foam. Balsa core actually has the best properties for decks as it has the highest compression strength, but everyone gets so freaked out about wood it is hard to get anyone to use it anymore. 

Depending on the span between deck supports, 12mm Okoume plywood soaked in epoxy with a layer of 7-10 oz cloth on top is pretty light. Plywood is easy to work with and relatively inexpensive. Done right and properly maintained, it won't rot in the next 20-30 years, isn't that long enough?

Transoms can be cored with plywood or foam, just make sure you use heavy foam. Big boats generally use 26 lb, you can probably get away with lighter core on a skiff. Same as decks, the glass provides the strength, not the core! Don't skimp on the glass in a transom. Make sure the transom laminate overlaps the bottom and the sides as they are the main supports. I hope the above makes sense. It's late and I am really tired!


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## trekker (Sep 19, 2015)

I used 1/2 h60 divinycell on my rear deck. 2 layers of 1708 on top and 1 on the bottom. 16" spans. Solid as a rock.


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## LWalker (Aug 20, 2013)

Boatdesigner said:


> In one of your earlier posts you mentioned the Coosa board provided the strength. That is completely opposite of the truth. The core just keeps the skins apart, they carry all of the load. When you calculate a foam/balsa cored laminate, you don't include the strength of the core, only it's thickness. If you are going with glass decks, I'd use Divinycell or Corecell foam. Balsa core actually has the best properties for decks as it has the highest compression strength, but everyone gets so freaked out about wood it is hard to get anyone to use it anymore.
> 
> Depending on the span between deck supports, 12mm Okoume plywood soaked in epoxy with a layer of 7-10 oz cloth on top is pretty light. Plywood is easy to work with and relatively inexpensive. Done right and properly maintained, it won't rot in the next 20-30 years, isn't that long enough?
> 
> Transoms can be cored with plywood or foam, just make sure you use heavy foam. Big boats generally use 26 lb, you can probably get away with lighter core on a skiff. Same as decks, the glass provides the strength, not the core! Don't skimp on the glass in a transom. Make sure the transom laminate overlaps the bottom and the sides as they are the main supports. I hope the above makes sense. It's late and I am really tired!


Hey Timm,

Good info. I am partial to wood and feel it is the best overall material(all things considered: cost, labor required, weight, etc). 

The Gougeon's have a good article comparing composite and plywood panels.

http://www.westsystem.com/ss/comparing-cost-and-weight-of-flat-panels/ 

From my research, composite panels are about 1/2 the weight, but 3x the price.


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## predacious (Sep 1, 2016)

Boatdesigner said:


> In one of your earlier posts you mentioned the Coosa board provided the strength. That is completely opposite of the truth. The core just keeps the skins apart, they carry all of the load. When you calculate a foam/balsa cored laminate, you don't include the strength of the core, only it's thickness. If you are going with glass decks, I'd use Divinycell or Corecell foam. Balsa core actually has the best properties for decks as it has the highest compression strength, but everyone gets so freaked out about wood it is hard to get anyone to use it anymore.
> 
> Depending on the span between deck supports, 12mm Okoume plywood soaked in epoxy with a layer of 7-10 oz cloth on top is pretty light. Plywood is easy to work with and relatively inexpensive. Done right and properly maintained, it won't rot in the next 20-30 years, isn't that long enough?
> 
> Transoms can be cored with plywood or foam, just make sure you use heavy foam. Big boats generally use 26 lb, you can probably get away with lighter core on a skiff. Same as decks, the glass provides the strength, not the core! Don't skimp on the glass in a transom. Make sure the transom laminate overlaps the bottom and the sides as they are the main supports. I hope the above makes sense. It's late and I am really tired!




let me see if I have this correct :

the core,it carries no load ?


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## predacious (Sep 1, 2016)

LWalker said:


> Hey Timm,
> 
> Good info. I am partial to wood and feel it is the best overall material(all things considered: cost, labor required, weight, etc).
> 
> ...



where did you get this information ?


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## Boatdesigner (Dec 9, 2009)

Just from experience, I would say Trekker's deck was overbuilt. I might lose one of the layers on the top. I usually calculate that stuff to make sure though! If you can handle the little bit of extra weight, making the upper laminate a little thicker is a good thing as it does take a lot of abuse over the years.

Luke, I recently spoke to someone who wanted to build an Osprey from composites, thinking he would save a bunch of weight. When I told him how light the hull skin was he was a bit surprised, 8mm of Okoume only weighs .84 lbs/sq. ft. Wood can be very light, but it does require supports that are pretty close together. That is why the Osprey has all those fiddly little stringers in the hull and the deck. None of the spans are over 8" or so, which lets you use real thin plywood. If you can't use lots of supports and need to go over a longer span, then the frp composites may be lighter as you can just use a thick core with thin skins. I would bet that Trekker can go 18" or more with his deck and still get good stiffness due to the thicker core combined with pretty heavy skins. I have worked for a number of production boat companies and many times our decks were 4.5 oz chop on top, 1/2" balsa core and a 24/15 fabmat on the bottom. Worked pretty good, but you had to make sure the hatches didn't warp due to the uneven laminate. On large spans we used the same laminate, but with 3/4" core. Depending on the wood you use, it's usually less expensive than composites.


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