Boat extension

Actually, you don't need a computer to make these trim adjustment calculations. Making moment to trim and PPI calculations is simple math, easily performed on a pocket calculator (even long hand if desired). With the plans in hand and a reasonable weight study (tedious by hand, but certainly doable), anyone with a high school education can preform these calculations and get the boat to trim out, right where you'd like the boot stripe to be painted. Yes, these calculations can be sped up with a spread sheet and/or other software, but (again) the OP has a limited ability in this regard, so . . . Unless significant and substantial changes to the plans are anticipated, plus the desire to perform these modification himself, there's no advantage to a virtual model. This in it's self is dangerous, as these packages, tend to lead the novice user into a false sense of security - meaning he can make wholesale changes to the design, with little understanding as to the ramifications of the changes, individually or on the whole. Fortunately, Albert will likely be working with a well known NA on the project, so all of this is moot, assuming he follows the plans and subsequent upgrades, performed by the NA.

 

PAR, my friend, again you're wrong. Nobody wants Albert to make a computer model, or do the calculations with a pocket calculator or a computer from NASA. What I am saying is that, and I thank you now to agree with me, is needed to do some calculations to verify that the elongated vessel has no problem the original boat had not. If that check is made by Albert, by a NA or by you, that's not my business. Thanks, therefore, for giving me the reason. It was hard but we managed, thanks.

 

TANSL with all respect - PAR is way more on the ball with this one. Lengthening a boat like OPs by 12% definitely is done by spacing stations and essentially scaling on 1 direction. And the impact is not that big of a deal and done all the time. Of course things like engine will not scale so small stuff like that have to be taken into account and yes of course there is a point where scantlings would need a review. Adding a section in the middle is pure nonsense in this context.

 

kerosene

Depends on the shape

 

Par states "You're correct Eric, it will be more stable"


Boat for a canal in EU maybe but they are heavy on the bottom also no waves and protected waters.
Boat stableness comes from width or you have a canoe.

 

kerosene, as things stand, I appreciate the friendly tone of your post.
I believe, and I repeat, 2 things:
- It is necessary to check the boat again, as I said from my first post.
- Since there is no mold built but only some plans, I think you can extend whatever direction you choose. It all makes sense, even what I say. Albert Jr will have to choose what he would look more profitable.
Cheers

 

myark, for what shapes can the unrolled panel shapes be simply stretched when the boat is stretched?

 

I think he meant it to me and used your quote as a reference. And yeah I agree that while the boat shape simply scales in onedir its more complex for a panel in several dimensions.

 

I quite like the classic style of the said lobster boat ,Our pelin was a similar layout .While I like the classic styling ,more modern layout is a bit better. By making forward cabin 2 bunks with 2 wardrobes and not encroaching into saloon you can move helm and dinette forward slightly ,placing wc and galley at the rear of saloon .Having wc forward is problematic for standing space while aft you can buy all sorts of units (rv and caravan )that fit nicely. That goes for the galley as well. So having an extra 3ft divided between cockpit and saloon keeps overall style in keeping in the said boat .

 

Maybe TANSL doesn't have the ability to use a calculator, without a laptop attached to it, but having learned with a slide rule, I can assure you, the functions are quite simple, the calculation very rudimentary and the process relatively uneventful, in spite of the insistence of those computer users, that have never built anything, though who knows, might have designed something one or twice..

 

PAR, will not waste my time to answer you.
If someone wants to refute your opinions and downs, I'd appreciate it. Seem more objective than if I do it
Cheers

 

http://www.amateurboatbuilding.com/articles/design/vdesign/vdesign7_tools.html

It took a while for the yacht design community to embrace the new way of designing boats. More exactly, there was a strong prejudice expressed by those who were stuck in their ways and reluctant to learn new methods.
In the early 90's, the Westlawn Yacht Design Institute began to accept CAD work and today, almost nobody drafts with paper and pen.
There is no excuse to keep using old inaccurate methods or to buy plans that require lofting.

 

Albert was considering a Glen-L Pot Luck http://www.glen-l.com/designs/workboat/potluck.html earlier in http://www.boatdesign.net/forums/boat-design/making-lobster-boat-ride-faster-47179.html

Glen-L already says "Can the hull be extended or shortened? Yes. Up to 10% by re-spacing the frames from the aft end of the stem to the transom a proportional amount. We do not recommend increasing the beam."

"What would be the pros and cons ?" is probably asking for pros and cons of this boat either as a 33' or stretched to a 36' to 37'.

 

Why Glen-L says it can be done up to a variation of 10% in length, without increasing the breath?. Perhaps because for highest increase (12% for example) have to reconsider the characteristics of the new boat.

 

scantlings probably come to play. naturally you can't stretch a boat limitlessly with same material thicknesses etc.