I asked this group before about extending a cosine wherry and got some
good responses. But I don't remember any comments regarding the beam
on it. I think I finally decided (but am still not 100% sure) that I
would like to make it 16' 3" instead of the original 14' design. With
the additional 2 feet plus should I also consider increasing the beam
proportionately?

Thanks,

Jay

What do you need the boat to do?
- carry X lbs. of people and stuff
- be stable enough to tolerate a hyperactive lab?
- be a faster rowing boat
- etc.

Stretching the boat in length only will increase the carrying capacity 16%
and improve it as a rowing boat in all but the windiest conditions.
At about 4', it's already wide enough to provide decent spread between the
rowlocks without outriggers.
If you need more than a 16% increase in displavement, i'd look at other
designs rather than widening the boat.

Regardng construction, the scantlings in the book look OK to me for a
stretch version, except that i'd make the breasthook and quarter knees of
3/4" or 1" solid stock and perhaps enlarge them a bit. Just adjust the
spacing between the station molds. If that pushes the spacing past about
18", 1/4" strips might be a bit wayward and you might make 'em a touch
(1/32") thicker.


"Jay" wrote in message
...
I asked this group before about extending a cosine wherry and got some
good responses. But I don't remember any comments regarding the beam
on it. I think I finally decided (but am still not 100% sure) that I
would like to make it 16' 3" instead of the original 14' design. With
the additional 2 feet plus should I also consider increasing the beam
proportionately?

Thanks,

Jay

The Cosine was also designed as an 18 footer

Brian

Jim,

On Wed, 16 Aug 2006 12:34:12 -0400, "Jim Conlin"
wrote:

What do you need the boat to do?
- carry X lbs. of people and stuff

Yes. An additional passenger and muskie fishing gear. Possibly a small
outboard or electric motor and battery too.

- be stable enough to tolerate a hyperactive lab?

Stable enough to tolerate my fat ass moving around trying to net said
muskies.

- be a faster rowing boat

Not necessarily faster, but it can't hurt.

- etc.

Stretching the boat in length only will increase the carrying capacity 16%
and improve it as a rowing boat in all but the windiest conditions.
At about 4', it's already wide enough to provide decent spread between the
rowlocks without outriggers.
If you need more than a 16% increase in displavement, i'd look at other
designs rather than widening the boat.

Regardng construction, the scantlings in the book look OK to me for a
stretch version, except that i'd make the breasthook and quarter knees of
3/4" or 1" solid stock and perhaps enlarge them a bit. Just adjust the
spacing between the station molds. If that pushes the spacing past about
18", 1/4" strips might be a bit wayward and you might make 'em a touch
(1/32") thicker.

IIRC 18" is the max spacing other than between the last station and
the transom but I don't have my drawing handy here at work.

Jay



"Jay" wrote in message
.. .
I asked this group before about extending a cosine wherry and got some
good responses. But I don't remember any comments regarding the beam
on it. I think I finally decided (but am still not 100% sure) that I
would like to make it 16' 3" instead of the original 14' design. With
the additional 2 feet plus should I also consider increasing the beam
proportionately?

Thanks,

Jay

On Wed, 16 Aug 2006 19:20:19 -0700, "Brian"
wrote:

The Cosine was also designed as an 18 footer

Brian


I only have the original book and pattern. Is the 18 footer design
available? Does it have a wider beam?

Jay

I have not looked the plans for a long time but I don't believe it was much
wider than the 14. I believe that Flounder Bay Lumber while it changed
ownership might be able to help you get those answers. The guy who designed
the boat is from Edmonds WA also.

Brian