1) the foam added to the bottom ( outside) the hull actually increased the hulls
displacement, therefore as the weigth only slightly increased (foam + glass) the
hull rose , thus solving the problem albeit with a possible stability problem as you mention.
The foam is really only "thick air" after all, and its easier to carve than thin air !!
2) I've one of those plans using extended hull lines of a pommy paddler showing that technique,
its main problem, I think, was the length/width aspect ratio was quite high, along with a narrow
hull.
3) right on !, one reason I use Wiper Motors is that they give me weight at or below the LWL thus
giving me free ballast and extra stability without resorting to dummy lead keels, that are often
used ( and needed) on scale true yachts. One nive featue of Ozzie Paddlers ( in general) is that
that they were not overendowed with superstructure, and generally made of light timbers
when compared to the weight of the Red Gum hulls
=======================
Extract from PJ's response :
but... the foam will increase buoyancy (i.e. lift the
hull/lower the waterline)...but placed on the underside of the hull
will in fact increase instability! Dai (Powell) here in Victoria has a
nice sidewheeler which sat a little too low in the water...the sponson
deck was just under the surface I recall...he "foamed and fibreglassed the
bottom" to lift the hull high enough so the sponsons were clear and the
wheels had correct immersion.
I have seen R/C model paddler plans deliberately drawing extra draft so as
to obtain correct immersion of the floats. Since it's all below the
water, nobody can really tell the diff..however, if a paddler hull is
carefully constructed with a clear idea of C of G, topside weight, and
wheel immersion, then you don't need to "cheat" on the draft.
Remember, build the superstructure LIGHT with a low C of G..and you
won't need to increase buoyancy!
Brett S Hallett
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