: Hi Joe,

: A very nice outlay of relative points.

: Here are my reactions with an intention of judging one against the other

: 1/Time to build

: It looks like a tossup to me

: 2/Weight/Balance

: external - is top heavy and over balanced(at least a 6x6,10x10better here)
: and requires fixed legs or is easy to knock over. With moving large
: awkward items around the shop, extra wt of the beam or upstands count.

: internal - centrally balanced and support points are flexible, not fixed and
: movable along the int

: 3/Expense

: semi tossup

: 4/ Construction ease

: semi tossup

: 5/ Mounted Forms

: ext - not yours (or necessarily so), but I think some use 2 forms for ea
: station. And I believe that means one of two approaches - a)after hull
: made, yak is removed from the aligned ext, flipped, and deck stripped w
: unaligned forms?-is this right? b)after hull made, hull and 1/2hull form
: ass/y removed to some other location, deck forms attached and aligned and
: stripped. What I'm getting at - is there time in the building process that
: unaligned forms are used or is there a time in the process that an
: unstiffened hull is laying around.

: int - forms mounted thruout building

: 6/Alignment and Constancy of Alignment

: Initial alignment is a tossup(I like your approach, but think mine kicks- but
: whatever)

: ext- have to align twice OR build hull from unaligned deck

: int - once only and aligned thruout bldg

: 7/Klutz Kontrol

: I put this in for amusement - I dropped my whole assy(unstripped) a couple of
: times. I think an external would really have gotten damaged

: 8/Floorspace/Bulk vs Workbench

: ext - takes up way more volume b/c of the ext beam and the ext upstands. And
: especially at the knee area and ends. But this negative is completely
: contradicted if this space is desirable as a workbench. My guess is that
: small established wkshops w/ one yak in progress at at time would prefer
: the minimal space used, and that larger shops w/ multiple yaks in progress
: would like workbenches for that project only. I think this one depends on
: the particular shop/work setup.

: int - less volume, see above. that could be good or not as useful.

: 8b/Rotation

: This is a benefit that is at least used by me for working horizontally on the
: sides of the yak for either routing, small patterns, or placing awkward
: strips so they won't fall initially. This factor is likely irrelevant to
: most builders.

: ext - fixed and very difficult to rotate

: int - not necessarily fixed and therefore more possible

: 9/Storage: Int - at most 1/4 the size(usually way smaller). I would say a
: significant difference. But if you have space, it may be a minimal factor.

: 10/Portability

: both can be wheeled but

: int - can be more easily lifted, rotated, manouevered, or even hung.

: 11/Strength/Stiffness

: tossup

: I think this is where the int is the most vulnerable to concern. And yet I
: say 'tossup' because if it is NOT stiff enough, it is an almost useless
: approach, requiring all kinds of external influences to be stiff - an
: abortion. As I am(nor have) not making a long yak yet, I partially rely on
: the experience of others to assess that it IS rigid enough and have also
: developed an approach that slightly increases the side to side stiffness.
: so: ext - way stiffer

: int - stiff enough

: 12/ Form setup

: tossup, (I would say int)

: 13/Form Rigidity

: ext - forms more exposed, distant from the support. Forms are on 'long'
: cantilevers(the upstands), are more floppy

: int - forms are fastened approx at their ctrs, are consequently more rigid
: and more accurately place. The rigidity has been esp helpful to me as I've
: taken the wood carving gouge and mallet to at least half of them to modify
: them for my particular processes. I don't think the ext would take it as
: well

: 14/Form removal

: In this, I think you imply that the hull is built on the unattached hull and
: forms. If so, the ext wins big time.

: ext - way better

: 15/Assembly Rigidity

: this only applies if my assumption that the deck is built on the unrestrained
: hull form assembly

: ext - flexible and weak for sanding, and fairing, and maybe unaligned for
: glassing - It depends on which you do first.

: int - strong and aligned thruout fairing and glassing.

: 16/Design Approach

: When I look at the yaks designed using the ext approach (not yours), I find a
: constant explicit division betw the hull and the deck. My guess is that a
: designer assuming the external defacto starts out with this separation in
: mind and thereby eliminates a whole array of alternative posibilities. The
: sheer is the sheer is the sheer and the hull and deck separate only along
: a simple curve.

: To me, it's an automatic design constraint - why does a kayak only have to
: split at a deck/hull, why only 2 yak pces, why are forms only one piece -
: lots of possibilities for undercuts etc w/ multiple pcs, why not
: approaches utilizing multiple sheers or no sheer. (I am certainly no great
: example, but have 2 'sheers' and am splitting the yak in a totally
: different and as yet not completely set location).

: So to get back, I think the int admits a little more conceptual freedom .
: This is obviously a useless factor to just about everyone.

: 17/ Strip design

: Aside from just following the historic and traditional separation of deck and
: hull, the ext hinders even strip design from smashing the barrier. With
: the ext, there is almost a predetermined process and w/ difficulty is the
: barrier crossed.

: So again, likely a useless factor to just about everyone. But think about
: Kent's flame yak - what if the flames were waves and they dribbled down
: from the deck thru the sheer to and up and down along the waterline.

: So in summary

: Basic tossups - time, cost, stiffness(!!!-has to be or nfg), form setup.
: trade-off is bulk vs workbench

: External superior - workbench, form removal

: Internal superior - wt/balance, alignment constancy, less bulk(volume),
: storability, rotation, portability, form rigidity, assembly rigidity, and
: maybe design and strip approach.

: For those with space - bulk, storage, (maybe portability) don't apply.

: For straight builders - form rigidity, and design and strip approach don't
: apply.

: And I feel that alignment constancy may be a debatable point sawoff.

: So from the above the main pt for ext is form removal and the int is
: wt/balance, maybe portability, maybe rotation for a few, and assembly
: rigidity.

: (And I just have to screw up the comparisons by saying that to me the int is
: a far simpler and more direct approach.)

In the post to shawn, just realized there are some interesting building constraints. I forgot I was dealing w/ one of them myself by orienting my strongback sideways in order to make the curvature and the other extends from what I called the design constraint to actually be more of a building constraint. The following are generalizations and any savvy builder could figure out ways around, but its fun to be absolute sometimes. So some more factors:

18/ Shallow Kayaks

Because the depth of the kayak determines the depth of the hull when removed from the external, if shallow, even the glassed assembly will be extremely weak and jittery to reference and build aligned and with smooth rocker. And w/ the internal, there are simple space constraints when you start curving. so:

ext - cannot build shallow kayaks

int - cannot build shallow kayaks with extreme rocker and/or large upturned ends.

19/ Low Sheer Constraint

for same reasons for the external above

ext - cannot build low sheer kayaks. like some sitontops, some surfskis, surfboots, and probably very difficult to impossible to build low sheer yaks like guillemots.

int - no problem - high sheer, lo sheer, big sheer , no sheer.

-mick