Stretching out the beam?

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njviking
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Stretching out the beam?

Postby njviking » Sun Nov 26, 2017 5:37 pm

New here with some questions about the Nor'wester plans.

I have a Parker 2520 now and pretty much want a 30 ft version of such. What I don't like about the Nor'wester plans is the fact that it only has an 8.5 beam. I'm pretty sure I know the answer I'm going to get, but I figured I'd ask .. Can I stretch it to 9.5 beam?

Thanks
Mark

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Re: Stretching out the beam?

Postby Hercdrvr » Sun Nov 26, 2017 6:20 pm

Nope, increasing beam is strictly forbidden around here. Nothing gets the forum stirred up faster.
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JoeM
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Re: Stretching out the beam?

Postby JoeM » Sun Nov 26, 2017 7:21 pm

I can't give an answer as far as if you can or can't. Still too new at this.

Are you planning on trailering the boat or keeping in a slip?

While many municipalities don't pay attention to the 8'6" max width now, it's on the books so if you plan on trailering it I would look into what permits you may need to avoid any tickets.
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Kevin Morin
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Re: Stretching out the beam?

Postby Kevin Morin » Mon Nov 27, 2017 12:10 am

njv'k'g, you "can" stretch the beam to a wider hull but you'd have to loft the entire boat (read: Redraw) the lines and that might be a fairly involved task?

What would happen to a change in beam without redrawing the other lines in Profile and Body plans? Well that is truly up for grabs! If a set of hull lines is changed in one view only- you're asking about the Plan View or Beam Overall (BOA) the entire (Glen-L Catalog design) boat design is "gone" as the waterlines, buttock lines, Profiles and Body Plan views are all changed too!

So, if you're good retrofitting an entire design, re-fairing, redoing the Table of Moments, righting moments, Cb, Cg, water planes and other "details" - go ahead change her beam!

On the other hand, if you have to ask the question, you do realize you have no hint of what's impacted by your "idea". So the answer becomes "What you're asking is not realistic if you can't redraw the entire boat's lines".

Some planing hulls can be lengthened a percentage of the LOA, without significant changes to the other lines- as long as the after run of the three principal lines are close enough to parallel. But except for that example, change in LOA, as extensions of reasonably long, fair lines- changing other lines will create a series of interacting changes to the other lines' views- that implies redrawing the boat.

Hope you'll still consider the design but explore giving the entire boat an even % multiplication- increase the entire table of offsets- not one set of lines (chine and sheer in Plan as I understand you're contemplating?). Make the design bigger in all three views (XYZ) and its a more reasonable plan modification- (wt and balance should be redone though ) and you're likely to have a much more successful boat.

Cheers,
Kevin Morin
Kenai, AK
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njviking
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Re: Stretching out the beam?

Postby njviking » Mon Nov 27, 2017 2:03 pm

I figured as much.
I was wondering about a % increase on the three views and just make it bigger. I guess that's really what I was hoping someone had already done.
I think I would be capable of lofting until the stem and buttock lines, I'm just not educated enough on the matter to tackle it.

I'm still going to order study plans to look at and if I don't find another plan that fits me; then I'll do it.

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Bill Edmundson
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Re: Stretching out the beam?

Postby Bill Edmundson » Mon Nov 27, 2017 3:15 pm

Mark

I took a Bartender 22 and scaled it up to 24', just over 6%. I redid the lofting table and changed in all 3 directions. It now has an 8'4" beam and a little more freeboard. I'm very happy how it runs. I scaled up all the dimensions: butts, stem, spacing... I did not scale the main side decks. This made the Cabin and cockpit wider. Glad that I did!

Bill
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kens
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Re: Stretching out the beam?

Postby kens » Mon Nov 27, 2017 4:20 pm

Most of the designs on this website can be stretched (or shortened) in length, but not beam.
The Parker looks like a Lobster or down easter. Is that so?
The nor'wester is a full planing deep-vee.

Do you want a lobster running bottom, or a deep vee?
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Re: Stretching out the beam?

Postby Steven r » Sun Dec 03, 2017 12:01 pm

Hi,
I wonder if you go from 100% to 125% on the printer why is every thing not in proportion or is it? Or is it its not in PDF? I believe long and thin is best as race boat would be. I have been looking at auto cad, and skan 2 cad so one can use a CNC as it needs to be DFX. I think? So I think you could make wider on the beam you could check by lofting if you have offsets, there is lots to think about but as usual you need to one step ahead or you will be told no! I have seen what I would like to build but no plans.
Steve.

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Bill Edmundson
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Re: Stretching out the beam?

Postby Bill Edmundson » Sun Dec 03, 2017 1:49 pm

There is another thing to remember when scaling up! A 1.062 scale up is 1.062x1.062x1.062. The boat is now 20% larger in volume.

Bill
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Steven r
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Re: Stretching out the beam?

Postby Steven r » Sun Dec 03, 2017 2:16 pm

Bill,
Please correct me if I'm wrong but by doing this to the stringers they stay the correct shape only larger?
Regards Steve.

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Bill Edmundson
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Re: Stretching out the beam?

Postby Bill Edmundson » Sun Dec 03, 2017 2:44 pm

Steve

You are correct the physical boat will just be larger. But, the displacement capacity of the boat will go up much faster than the weight of the boat.

Bill
Mini -Tug, KH Tahoe 19 & Bartender 24 - There can be no miracle recoveries without first screwing up.
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Steven r
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Re: Stretching out the beam?

Postby Steven r » Sun Dec 03, 2017 2:55 pm

Bill,
I need to think about this, maybe build it heavier and stronger? Larger power unit? Or stretch it?
Steve.

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chugalug
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Re: Stretching out the beam?

Postby chugalug » Sun Dec 03, 2017 3:12 pm

:? my guess would be to build bigger designed hull and put your own designed cabin on .just my 2 cents
Last edited by chugalug on Mon Dec 11, 2017 2:40 pm, edited 5 times in total.
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Bill Edmundson
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Re: Stretching out the beam?

Postby Bill Edmundson » Sun Dec 03, 2017 3:20 pm

Steve

Lots of things to think about. I'm not a Marine Arch or Eng. I don't work for Glen-L. There are things that I might try. But! I can't tell someone else to do!

Bill
Mini -Tug, KH Tahoe 19 & Bartender 24 - There can be no miracle recoveries without first screwing up.
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Steven r
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Re: Stretching out the beam?

Postby Steven r » Sun Dec 03, 2017 3:32 pm

Bill,
I understand where you are coming from. I like playing about for myself I have done a lot of it in my life!
Steve.


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