On Jun 5, 10:34 pm, NSS wrote:
I'm looking to build a 20' v-bottom spritsail skiff, using stitch and
glue. Pretty much straight from the NC Maritime Museum plan #5:

http://us.st11.yimg.com/us.st.yimg.c...00216_1952_134...

This will be an open boat - structure will include short deck at the bow
(a foot or two long), with a bulkhead at the aft end of it; a thwart at
the mast, centerboard trunk, thwart at aft end of trunk, and thwart in
rear, in front of removable sternsheets. No side decking, just a strong
rail/gunwale. I will probably make gussets on either side of each
thwart, extending from rail to chine, and box in under the thwarts
(flotation filled). As per the traditional skiff, there will be a
relatively heavy deadwood starting at the aft end of the centerboard
trunk and extending to the rudder. No keelson forward, probably a
minimal one aft to bolt the deadwood through to.

I will epoxy/glass the exterior, and possibly glass the interior too
(haven't decided yet). Ply will be Okoume BS1088.

I'd like to make this boat as light as possible for maximum speed; it
will be basically a toy for the Beaufort NC area, Bogue Sound, etc.

I'd like it to be as stiff as possible for maximum performance, moreso
than for great seaworthiness. Note the rig will be a bit taller than
that shown in the plans; the norm for the museum built boats has been
15' or so mast height, vs. the 12' spec'd for the workboat in the plans.

So my question is, what thickness plywood should I use? The original
boats were planked with 7/8" juniper, with quite a few frames holding
the planks in place. With S&G I will have no frames, other than the
aforementioned structure.

I was leaning toward 3/8" for bottom and side panels, but am wondering
if I should make the bottom panel 1/2" just to stiffen things up, and
for walking around on (hoping to get away without any floorboards).

Any opinions?

Thanks in advance,

NSS

Well, if you run thin stringers inside the floor, maybe 14 inches
apart and bulkheads evey 2 feet you could probably get away with 6mm
(1/4inch"). A sheet of 6 oz. glass over the bottom for scratch
protection. Certainly with curved sides like that I would use the 6mm
for the sides. And if you are nervous, 9mm (3/8") inch on the bottom
with a lighter sheet of glass, maybe 4 oz tight weave. The two biggest
mistakes folks make with s+t is overengineering it, and over coating
it. Remember, thickness of epoxy really does not add strength on it's
own. Do a test or two with a a 2foot x 18" piece of 6mm, glass it,
support it on all four sides (like stringers and bulkheads) stand on
it. see what you think! And two, using glass and epoxy instead of wood
for structure. Hope this helps.

On Jun 6, 8:54 am, wrote:
On Jun 5, 10:34 pm, NSS wrote:





I'm looking to build a 20' v-bottom spritsail skiff, using stitch and
glue. Pretty much straight from the NC Maritime Museum plan #5:

http://us.st11.yimg.com/us.st.yimg.c...00216_1952_134...

This will be an open boat - structure will include short deck at the bow
(a foot or two long), with a bulkhead at the aft end of it; a thwart at
the mast, centerboard trunk, thwart at aft end of trunk, and thwart in
rear, in front of removable sternsheets. No side decking, just a strong
rail/gunwale. I will probably make gussets on either side of each
thwart, extending from rail to chine, and box in under the thwarts
(flotation filled). As per the traditional skiff, there will be a
relatively heavy deadwood starting at the aft end of the centerboard
trunk and extending to the rudder. No keelson forward, probably a
minimal one aft to bolt the deadwood through to.

I will epoxy/glass the exterior, and possibly glass the interior too
(haven't decided yet). Ply will be Okoume BS1088.

I'd like to make this boat as light as possible for maximum speed; it
will be basically a toy for the Beaufort NC area, Bogue Sound, etc.

I'd like it to be as stiff as possible for maximum performance, moreso
than for great seaworthiness. Note the rig will be a bit taller than
that shown in the plans; the norm for the museum built boats has been
15' or so mast height, vs. the 12' spec'd for the workboat in the plans.

So my question is, what thickness plywood should I use? The original
boats were planked with 7/8" juniper, with quite a few frames holding
the planks in place. With S&G I will have no frames, other than the
aforementioned structure.

I was leaning toward 3/8" for bottom and side panels, but am wondering
if I should make the bottom panel 1/2" just to stiffen things up, and
for walking around on (hoping to get away without any floorboards).

Any opinions?

Thanks in advance,

NSS

Well, if you run thin stringers inside the floor, maybe 14 inches
apart and bulkheads evey 2 feet you could probably get away with 6mm
(1/4inch"). A sheet of 6 oz. glass over the bottom for scratch
protection. Certainly with curved sides like that I would use the 6mm
for the sides. And if you are nervous, 9mm (3/8") inch on the bottom
with a lighter sheet of glass, maybe 4 oz tight weave. The two biggest
mistakes folks make with s+t is overengineering it, and over coating
it. Remember, thickness of epoxy really does not add strength on it's
own. Do a test or two with a a 2foot x 18" piece of 6mm, glass it,
support it on all four sides (like stringers and bulkheads) stand on
it. see what you think! And two, using glass and epoxy instead of wood
for structure. Hope this helps.- Hide quoted text -

- Show quoted text -

I am a long time builder of the spritsail skiffs. There are several
things involved in what you are attempting to do. The beam on that
boat and its sail area is about right for the boat. Built in
traditional wooden construction, the weight lends some safety to
sailing in those SW winds 15 knots and better. The original sail plans
do not take into consideration a traditional reefing, and needs to be
reefed the old fashion way.


If you increase your mast height, you can also increase the sail area
and use the reef points in the sails which is absolutely mandatory for
that boat. If you build that boat out of Okume plywood, you will
indeed need to use some structual glass which will add some weight,
and not just some finish cloth. . The boat will be too lite unless you
do this.

Another issue will be the entry portion of the bottom at the bow using
plywood in sheets, which is not possible. You will need to use small
strips, laminated and glued up.

On Jun 6, 12:10 pm, wrote:

If you increase your mast height, you can also increase the sail area
and use the reef points in the sails which is absolutely mandatory for
that boat. If you build that boat out of Okume plywood, you will
indeed need to use some structual glass which will add some weight,
and not just some finish cloth. . The boat will be too lite unless you
do this.



Sounds then like the boat just should not be built light weight at
all.

On Jun 8, 7:00 pm, wrote:
On Jun 6, 12:10 pm, wrote:


Sounds then like the boat just should not be built light weight at
all.


Many people attempt to change knowns. In these hulls, the older ones
that meet and fit this design according to plans, used a topsail for
additional sail area in lieu of increasing the mast height and sail
area. The other side of the coin is that you have addtional rigging to
deal with too. Keep in mind that most all the traditional built boats
were built using oak, hear pine, and many other heavy timbers and add
that to the issue that these boat used to reside in the water
fulltime, which is not the case now.

On the other side of the coin, in lite winds, the boats were under
sailed, but never meant to be race horses, just work boats which on
occasions were used for weekend races. Some were even built for
pleasure by the older guys as these were the pickup truck of old days.
Every single boat is a compromise in one form or the other.

If a person truely does not like solid wood scantlings, just use
heavier plywoods, which is nothing more than an experiement in the
wrong hands of amateur or backyard designers. [insert wink]

Take one thing from this conversation, shallow draft boats, no ballast
are tender boats in the wrong weather and varible weather conditions
such as happens along Bogue Banks. Tidal changes causes what should be
a nice afternoon sail to a wet one.

On Jun 9, 8:16 am, wrote:


If a person truely does not like solid wood scantlings, just use
heavier plywoods, which is nothing more than an experiement in the
wrong hands of amateur or backyard designers. [insert wink]



wink indeed

On Jun 9, 10:16 am, wrote:
On Jun 9, 8:16 am, wrote:



If a person truely does not like solid wood scantlings, just use
heavier plywoods, which is nothing more than an experiement in the
wrong hands of amateur or backyard designers. [insert wink]

wink indeed

Just wait a frekin minute here. Do we somehow know each other? [insert
tongue in cheek gremlin]

On Jun 8, 4:00 pm, wrote:

Sounds then like the boat just should not be built light weight at
all.

Consider building it lightweight but adding a water ballast tank in
the bottom that you can fill or not depending on the weather.