Stretching an Argie 15 to an Argie 16.5?

[cobalt]

Hello all,
I just ordered plans for the Argie 15. I’m wondering if it’s an ok idea to scale these but 10% to give a touch more length and breadth?

I really like the design, but I’m thinking a little extra won’t hurt… I’m a big guy…

Thoughts? Thinking I might just redraw in CAD and scale by 1.1x?

THANKS


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[David Cockey]

If you are planning to scale in all directions by 10% then the panel shapes will stay the same. But note that scaling by 10% in all directions increases the volume by 33% so the scantlings (sizes of the wood) should be increased. Also other details may need to be reworked. So what seems like a simple scaling becomes a design project.

Scaling in only one or two directions means that the shape of the panels will change.

Have you contacted Dudley Dix to inquire if he might be interested in developing an Argie 16.5 design?

[Edward Pearson]

Just build it as is. It's 15'6" x 6ft with a sleeping platform for someone 6'3". At 100kg you can trolley launch it. Make it bigger and it's a whole can of worms. It'll be designed for two people, so one big guy will still have it under standard design displacement. It's a good size already. 17ft x 6.5 ft is a much bigger boat. 'Good classic cruising sailing dinghy seaboats' cluster around 16 x 6 x 10sqm. Solo 14ft is preferable to many. If your a big guy you should power it just fine as is. Its Dudley's biggest selling design and regarded as a good one, best not mess with it or you might be out of the bullseye of a trained naval architect who's job it is to know of such things. If you want the best boat, build it exactly to plan. That may take it's own kind of mental focus over a couple of years. If it's not the right boat they'll be something else that is.

If you want reasons not to...a longer wider boat will be getting on the wrong side of self righting possibilities solo from an inversion if its tanked, it'll have more wetted area, but the rail ballast (you) won't be bigger if you did put more SA on it, it'll be more of a handful getting it in and out, you'll spend a load of time figuring where the sail and boards need to be. None of the provided frames will be right and you'll have to loft it. You won't now where the waterlines going to be exactly and it'll be fairly worthless when you sell it as it won't be 'an Argie 15' to the market. It's a 'simple' boat so keep it simple and build it as is fairly briskly to keep it sweet. Boats that owe you a load of time and work can dissapoint.

[alkorn]

The Argie is not meant to be lofted, but built from precut panels. Since the panels lie along curves, you can't just increase their length by n% and expect everything to fit together correctly.

[BC Bill]

Maybe take a look at that Salmo 15.2 a couple threads down?

[Wayne Poulsen]

The Argie is not meant to be lofted, but built from precut panels. Since the panels lie along curves, you can't just increase their length by n% and expect everything to fit together correctly.

Correct...
if you increse all panels by the same factor they will fit together and the boat volume will be increased by the factor cubed ... so 10% will make a 33% bigger boat.
Remember that it will be a DIFFERENT boat and it might be just the right one for YOU.
Say ..If a 165lb rower found the original just right, a 10% stretch (in 3ds) might be the "Goldilocks" solution for a 220 pounder?

[cobalt]

The Argie is not meant to be lofted, but built from precut panels. Since the panels lie along curves, you can't just increase their length by n% and expect everything to fit together correctly.

yes, all dimensions would need to be stretched so it doesn't change the shape, jus the size.

I did send an email to the designer too. I can't believe I'm the first to ask this. As noted it is a very popular design. It must have been done somewhere along the way? right?

[cobalt]

Correct...
if you increse all panels by the same factor they will fit together and the boat volume will be increased by the factor cubed ... so 10% will make a 33% bigger boat.
Remember that it will be a DIFFERENT boat and it might be just the right one for YOU.
Say ..If a 165lb rower found the original just right, a 10% stretch (in 3ds) might be the "Goldilocks" solution for a 220 pounder?

that's what I'm looking for: the right boat for me.

[stromborg]

What is it about the Argie 15 that makes it so attractive and yet appear too small? There are innumerable boat plans of about this size and capability that one could build without the added complexity of stretching it. Hard to know what the unintended consequences will be until it is too late. Then again, it might be just fine.

[cobalt]

that's a good question. Here's what I like about it:
1) simplicity of build: I don't what to spend 3 years building...
2) lots of sealed buoyancy/dry storage: I'd like to use if for Maine Island trail type of cruising.
3) family friendly enough
4) I want to rig it with a loose footed lug and that variation is well tested.
5) I like the profile. It's not the prettiest boat, but its not ugly. I think he does a nice job hitting a balance between simplicity and nice lines. I can't abide an ugly boat. (good thing for me my wife has lower standards in husbands).

Why I want it bigger:
1) I'm a bigger guy: 6'2" 300lb.
2) My daughter gets very nervous when things are unstable... I want to give her every chance to have a good experience. She has Down syndrome and it affects her balance.
3) I want to do some coastal cruising and a little extra WL and mass can't hurt if it gets a little lumpy out there...

I normally overthink things and I probably should just go ahead and build it to plan, but I figured it doesn't hurt to ask...

[cobalt]

So... the word from Mr Dix is this:

What you describe is possible but I don’t know that you really need it. I used to be a touch more than 6’2” but have shrunk a bit over the years. I am slim though, at 165lb. If you want to sleep on an air mattress in the cockpit then it may be a bit snug if you are heavily-built as well as being tall.

The Argie 15 is a big dinghy and capable of carrying a good load. I have sailed mine with three adults, with plenty of room for a few more. I have seen videos with 5 or 6 adults and an adult with about 8 young students. But if you feel that the extra space will be worth it, that will be OK. The 6mm skin can take it.

[Wiley Baggins]

I don’t normally recommend something so far from the ask, but I think a strong argument could be made for Welsford’s SCAMP design.

https://smallboatsmonthly.com/article/scamp/

Definitely a bigger project, but hopefully not three years of work.

[cobalt]

I don’t normally recommend something so far from the ask, but I think a strong argument could be made for Welsford’s SCAMP design.

https://smallboatsmonthly.com/article/scamp/

Definitely a bigger project, but hopefully not three years of work.

Very familiar with scamp and her big sister long steps who’s study plans I purchased. Both look great.


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