Boat Builder Central - Builder Forums

I received a telephone call and email with the following question for Jacques: "I was wondering if the CX25 could be stretched to 28ft (or to add an additional 3 feet to the planned CX25 version)?" Jeff

That question keeps coming back.
Yes it is possible but not easy.

Seeing as the question pops up every so often, maybe it's time to design the CS28/CX28?

I second that thought. Maybe with a 11 - 12 foot beam?

Looking back at the posts regarding the CS25, a longer version has been requested since at least 2005. Jacques has also mentioned recently (within the last few years, anyway) that a longer and wider version is coming, but he consistently refuses to give any sort of timeline for when that might happen. That does seem to be his stance on all new plans and/or modifications.

That said, as the question has popped up numerous times, he has also said that stretching the CS25 (and other designs) by up to 10% is doable by simply multiplying all measurements in the plans by 1.1. That would result in a CS25 of 27.5' length and 9.35' beam. Whether that can be stretched further to the full 28' I don't know (that would be a 12% enlargement to 28' length and 9.52' beam), but I recall him stating that it should be possible in a post somewhere.

I'd want him signing off on it if going for the full 28', but that's me.

Take the metric CX25 plans, upscale by 10%, add a 6” bowsprit and bingo (!), you have a CX28 !!!

A 28 footer is BIG for a home build. I suspect the limited market is the reason Jacques doesn't get enthusiastic about doing a new design!

Exactly right!

I don't blame him as he needs to be enjoying his semi-retirement!

From past posts, the design work takes a good bit of time. Not as simple as adding a couple of feet...

BarraMan wrote: ↑Sun Jan 06, 2019 6:38 pm A 28 footer is BIG for a home build. I suspect the limited market is the reason Jacques doesn't get enthusiastic about doing a new design!

That's true, but seeing as the alleged demand has been there for at least 13 years and people build other 28 foot designs, maybe there's some merit in doing it? I don't know what would be required for a redesign, but I expect it to be a lot of work even though the smaller versions already exist.

BarraMan wrote: ↑Sun Jan 06, 2019 6:38 pm

A 28 footer is BIG for a home build. I suspect the limited market is the reason Jacques doesn't get enthusiastic about doing a new design!

Correct. I have to choose where to invest my design time and potential sales are a big factor.

Jacques,

I am currently in the middle of building my practice boat to get ready to do the scaled CS25 and just wanted to say some full on CS28 plans would be awesome!

I keep thinking about that but I am in the middle of redesigning some of my old plans including some for foam sandwich.
I was stuck for 2 weeks just updating software which required a new computer, 3 new programs and changing the attributes of all my existing files!
I am almost there with the update of the XF22 which is also a scaled up boat.

from my finding.....

Scaling the CS25 10% and Stretching by a foot is easy on paper.... the draw backs are as follows:

1-Much more material
2-the scantling spacing needs to be adjusted to accommodate the larger size (Should have a Naval architect do this)
3-Stringer thickness should be increased to a min of 1.5"
4-Need another layer of 12 oz 50" glass all around inside and out
5-Use 12" Biaxial tape where it calls for 6" tape
6-transom thickness need to be a min of 3"

Good luck!!!!!

Did you see this:
http://bateau2.com/howto/scaling.php

I wrote that a couple years ago.

hbav984 wrote: ↑Mon Feb 25, 2019 10:36 am from my finding.....

Scaling the CS25 10% and Stretching by a foot is easy on paper.... the draw backs are as follows:

1-Much more material

Yes for the plywood, my nesting is all messed up but not much for glass and resin.

2-the scantling spacing needs to be adjusted to accommodate the larger size (Should have a Naval architect do this)
3-Stringer thickness should be increased to a min of 1.5"
4-Need another layer of 12 oz 50" glass all around inside and out

The CS23 and CS25 have the same hull shape but scaled. I designed a 24 and did separate calculations for each. Ideally, the frames/bulkhead spacing should be adjusted = big job. Stringers can be thicker but not really important, it's the glass that counts. I should recalculate all glass, skins and tabbing and will probably end up with one more layer 12 oz. in and out. That's a guess, nothing else than a guess.

5-Use 12" Biaxial tape where it calls for 6" tape
6-transom thickness need to be a min of 3"

Sorry no. The transom thickness is fine and the transom glass goes by the rules for the bottom.
The small tape is just for accommodations and details, not structural.

Thanks Jacques,

Guess most of money was spent on scantling layout....(BTW-I did offer to pay you to do it).

All the other info he provided like stringer thickness and transom thickness is not really needed but will anyway but the additional layer of glass is a must. I was doing this anyway regardless because i'd rather have the additional strength.

Well,
Now folks will get see a Scaled, Stretched CS25. It's called the CSS28. Carolina Super Sportfisher!!!!