51205Re: [bolger] Re: How would Mr Bolger update Cynthia J?
- Oct 17, 2006Graeme--
It would be nice if all the things we want could be combined in a very short boat. Here are the problems that must be addressed in very smallboats.
1) On small boats, crew weight makes up a very large portion of the boat's total displacement. Placement of crew weight has a major impact on performance.
2) A 'cabin' needs to be long enough so that an adult can lie down--for average folks, this is around 75 ". If two people are to sleep in the cabin, the sleeping area should be between 42'' and 48' wide at the head and at least 36" wide at the foot.
3) There are three possible ways to get a decent cabin in a very short boat. You can have a cockpit behind the cabin; this will put crew weight in the back of the boat, possibly trimming the boat down by the stern. You can stack the cockpit on top of part of the cabin (examples are Peephen, Lynx, and the origunal West Wight Potter). You can combine the cabin and cockpit, sailing from inside the cabin (Birdwatcher, Supermouse, and several of Michalak's designs).
4) One of the things that drove the Cynthis J design was to have a very simple boat which was styled to look sort of like a Cape Cod Catboat. (And I think that PCB was very successful in this regard.) I know that Cynthia J's looks were (and are) one of the main reasons that I continue to admire this design. The desire for this catboat effect precludes a Birdwatcher cabin (which PCB tried, without success on the Flatfish design).
If I were going to play naval architect and revamp Cynthia J, I would move the main bulkhead forward and add a bulkhead and deck to the aft end of the cockpit. This would move crew weight forward. I would then close in the seats and cut holes in the bulkhead to create two quarter berths (these would not be very satisfactory and would often be damp, but what can you expect). Lastly, I would beef up the bottom to as much as an inch, adding a fair amount of ballast. Even with all this, Cynthis J is a sailor for sheltered waters, and I would consider her a character daysailor with the capability for an occassional one night cruise.
----- Original Message -----
Sent: Monday, October 16, 2006 10:51 PM
Subject: [bolger] Re: How would Mr Bolger update Cynthia J?
Ok, Ive read that MAIB article now and it hasn't changed my
perspective on Cynthia J very much, if any. The boat would still be
better, from a self rescuing and comfort point of view, for updates
made along the lines of Otter ll and similar. Yep, there is little
point in modifying Micro in the current Cynthia J direction, and
losing the stability and offshore capability, but Cynthia J would
benefit enormously from small attention to bouyancy and ballast.
PCB suggests the increased bottom thickness, and some extra
flotation in the quarters, also the 290lbs water ballast Rick
included to stop her going over and flooding like Martha Jane un-
revised, and Anhinga. I think a bow well would be better than a mast
slot alone as he suggests. The forward frame, middle bulkheads,
companion way, and storage mentioned in earlier posts would be
worthwhile little modifications IMHO.
In this article I think PCB looks at this hull as a big family's day
sailing dinghy rather than the comfy camp cruiser she might be. He
observes that more than one up, indeed with only two crew, it is
hard to trim the boat as it should be. If the seating places two
crew's weight too far aft of the C.O.B might not correct placement
of stuff stored in the cuddy balance it?
On the other hand, if the cabin is shortened to allow forward
extension of the side seats a comfortable cabin is lost for little
gain. This hull is not of his advanced sharpie type as PCB implies
in the article. It is a flat iron, as I understand the term. It
follows H I Chapelle's doctrine for sharpies of a long, dead-flat
run to the turn of the bottom. As such, crew weight placed further
than just a bit forward of where the seats are now will have the
undesirable effect of burying the chine forward with all the bad
follow-on effects that PCB has warned of so often. So, if crew sits
forward extra weight will have to be placed in the stern, and the
cabin is gone. With more crew this could be easily arranged, and
would suit, but it then is a very high sided dinghy.
As a cuddy camper this boat would be so good. Awaken, coffee, then
so easily bulk sail is hoisted to ghost off on the day's adventure
with the breeze hardly stirred in morning's first light.
--- In email@example.com, "pvanderwaart" <pvanderwaart@...>
> ...In the MAIB that arrived at my house yesterday, PCB says he
> give the boat a mast slot like the Chebacco, etc. I did find
> the mast to be a little closer to the end of my range of
> than I liked. He also suggested reducing the size of the cabin.
> As to major modifications to the design, I wonder if it makes much
> sense to take that approach. PCB's ply boat techniques have
> lot, and a new design to the same spec would be a lot different.
> there is little point in modifying it in the direction of Micro.
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