Subject: Re: [harryproa] Re: New liveaboard design in 3D
From: Gardner Pomper
Date: 2/20/2009, 2:23 PM
To: harryproa@yahoogroups.com.au
Reply-to:
harryproa@yahoogroups.com.au

Hi,


Well, it is really hard to get to a bruce number calculation, since I don't seem to be able to even get close on calculating weight, but I am hoping to get just about 1000 sq ft of sail, vs the 774 on visionarry. The harryproa web site says that Blind Date empty has a bruce number of 2, and fully loaded with 8 people it is 1.7. I figure those 8 people make up most of the weight difference between Blind Date and Rare Bird.

Anyway, until I can calculate the weight better, I won't know. Just "give me as much sail as I can get under the bridges" seems to be my current design spec <grin>

In terms of shunting the rig, I am starting to compile a list of things you need to do when shunting a cruising proa, and 1 extra set of sheets doesn't seem like it makes that big a difference. Maybe because it is actual physical effort, not just things to remember.

- Gardner

On Fri, Feb 20, 2009 at 12:00 PM, Mike Crawford <jmichael@gwi.net> wrote:


  I'd say a major factor in choosing a schooner rig is maximum mast height. 

  If you want to be able to travel down the ICW, the maximum height off the water is roughly 60' (or up to 64' if you want to be restricted to a low moon tide).  To get a bruce number close to 2 on a boat with liveaboard amenities, you'll probably have to go noticeably past that limit.

  Two 60' masts, though, should give nice performance.  And as Mike points out, a lower center of effort.

  Shunting a schooner rig will take more effort than an easy rig, but I'll bet it will take a lot less effort than tacking or gybing a catamaran that's getting its sail area from a large code 0 or a-spin.  Plus, it will maintain as much of that massive sail area upwind as you'd like to use, which can't be said about a traditional spritsail plan.

  The sheet loads will definitely be higher on a schooner than with an easy rig, but with the fixed booms, at least they'll be a lot lower than with a traditional multihull main. 

       - Mike




Gardner Pomper wrote:

Well, it started with the idea of the cockpit sliding through to get a narrower collapsed beam, but then the cockpit got too big. Next was the idea of the dinghy loading through it, but then I didn't have space to stand up in the single cabins. So then it was an easy way to get from the boat to the dock, but I lowered the tops of the  lw hull, so that isn't as important. Maybe it should just go away <grin>.


As for the easy rig, it seemed stronger to attach the masts by the beams, instead of beefing up the center of the hull, but mainly it was for increased sail area. I figure this is going to be a relatively heavy harry and I live in an area with light winds, and there is no convenient way to hoist extra sail, so I thought I would go with the biggest sail plan I could and reef alot.

Thanks for checking it out!

- Gardner


On Fri, Feb 20, 2009 at 10:49 AM, Michael Gehl <mike@vail.net> wrote:

Gardner, 


   Maybe I missed it, but why do you have the notch in the leeward hull? I would thing from a structural and simplicity standpoint, it may be better to eave the top level and add a sideways-sliding hatch. Don't remember why you chose not to use an Easy Rig - the sheeting loads and coordination requirements will be greater. Perhaps the lower CoE was the reason?

Also, the beams look a bit willowy. I suspect a larger cross section would provide greater stiffness and a weight reduction.

Mike


On Feb 20, 2009, at 7:06 AM, Gardner Pomper wrote:

Google Sketchup is free, it runs on Macs and PCs and it integrates with google earth, so once you are done with your model, you can put it in various spots on the earth. When I am done, I want to put it at my dock (it won't fit, but maybe I will make a sketchup model of changes I need to the dock).


Ok, I uploaded the sketchup files for both the liveaboard and the camper, in their respective directories.

There are LOTs of videos on how to use the features of sketchup on youtube, so it make it really easy to learn.

- Gardner





__._,_.___
Recent Activity
Visit Your Group
Y!7 Toolbar

Get it Free!

easy 1-click access

to your groups.

Yahoo!7 Groups

Start a group

in 3 easy steps.

Connect with others.

.

__,_._,___