OB21 possible?

Ask questions before buying our plans or request a new design. Anybody can post here
User avatar
jacquesmm
Site Admin
Site Admin
Posts: 27002
Joined: Wed Aug 14, 2002 1:00 am
Location: Florida USA
Contact:

Re: OB21 possible?

Post by jacquesmm » Mon Apr 15, 2019 12:35 pm

Good plan.
Study the nesting drawing. I guess you will need 2 extra sheets of 6 mm (there is room for larger bottom panels) and one 10 mm for the extra frame.
Maybe 2 extra 10 mm because of the longer stringers.

I don't always get involved in the discussions on the forum especially when the other builders give good advice but here, I see an idea that may be attractive to other builders. If I scale that drawing, I will add the sheets to the OB19 package and advertise it as a OB21 option.


Jacques Mertens - Designer
http://bateau.com

Jondavis
Frequent Poster
Frequent Poster
Posts: 55
Joined: Fri Jul 20, 2018 5:00 pm
Location: North Carolina

Re: OB21 possible?

Post by Jondavis » Mon Apr 15, 2019 12:38 pm

jacquesmm wrote:
Mon Apr 15, 2019 12:35 pm
Good plan.
Study the nesting drawing. I guess you will need 2 extra sheets of 6 mm (there is room for larger bottom panels) and one 10 mm for the extra frame.
Maybe 2 extra 10 mm because of the longer stringers.

I don't always get involved in the discussions on the forum especially when the other builders give good advice but here, I see an idea that may be attractive to other builders. If I scale that drawing, I will add the sheets to the OB19 package and advertise it as a OB21 option.
I understand that you would be a busy guy if you answered 100% although you do a pretty good job I have spent many hours here ready threads and always see your presence. While I have you you here how do Feel about closing the transom in and adding a bracket if the boat is made 21’ in length I’ve read that’s the minimum length you like to do a bracket on.
Fs14-ls splashed 2-25-19

Jondavis
Frequent Poster
Frequent Poster
Posts: 55
Joined: Fri Jul 20, 2018 5:00 pm
Location: North Carolina

Re: OB21 possible?

Post by Jondavis » Mon Apr 15, 2019 1:02 pm

Just purchased plans for an ob19 ready to get started!!
Fs14-ls splashed 2-25-19

cbdigh
Frequent Poster
Frequent Poster
Posts: 29
Joined: Mon Mar 18, 2013 2:10 pm
Location: Cherryville, NC

Re: OB21 possible?

Post by cbdigh » Fri Jul 26, 2019 7:09 am

I’ve asked before about an ob21 and would for sure buy a set of plans! Also curious about thoughts on engine bracket.

piperdown
Very Active Poster
Very Active Poster
Posts: 886
Joined: Fri Jun 22, 2018 12:35 pm
Location: Kansas

Re: OB21 possible?

Post by piperdown » Fri Jul 26, 2019 9:39 am

jacquesmm wrote:
Mon Apr 15, 2019 12:35 pm
Good plan.
Study the nesting drawing. I guess you will need 2 extra sheets of 6 mm (there is room for larger bottom panels) and one 10 mm for the extra frame.
Maybe 2 extra 10 mm because of the longer stringers.

I don't always get involved in the discussions on the forum especially when the other builders give good advice but here, I see an idea that may be attractive to other builders. If I scale that drawing, I will add the sheets to the OB19 package and advertise it as a OB21 option.

Jondavis wrote:
Mon Apr 15, 2019 1:02 pm
Just purchased plans for an ob19 ready to get started!!

Definitely going to follow along on this one!!!
Eric (aka, piperdown)

"Give an Irishman lager for a month and he's a dead man. An Irishman's stomach is lined with copper, and the beer corrodes it. But whiskey polishes the copper and is the saving of him." --> Mark Twain

User avatar
jacquesmm
Site Admin
Site Admin
Posts: 27002
Joined: Wed Aug 14, 2002 1:00 am
Location: Florida USA
Contact:

Re: OB21 possible?

Post by jacquesmm » Tue Jul 30, 2019 12:46 pm

cbdigh wrote:
Fri Jul 26, 2019 7:09 am
I’ve asked before about an ob21 and would for sure buy a set of plans! Also curious about thoughts on engine bracket.
Brackets: 21' is the lower limit in my opinion. I would not do it.
Jacques Mertens - Designer
http://bateau.com

Matt Gent
Active Poster
Active Poster
Posts: 396
Joined: Sat Jan 05, 2008 7:54 am
Location: PSL, FL

Re: OB21 possible?

Post by Matt Gent » Fri Aug 02, 2019 3:08 pm

Jondavis wrote:
Thu Apr 11, 2019 2:54 pm
I’ve contemplated building a c21 and cutting the sheer down like this but I’m thinking it’s a deeper hull than I’m looking for we do a lot of intracoastal cruising and beach the boats a lot. I have a 22’ very deep vee now and I’m trying to get away from the rock and roll that comes with the deeper boats.
C21 is not a particularly deep-V at all at 12deg, like most boats here. It just has high gunnels with the second topsides panel. It would make a decent bay boat by just omitting the upper panel.

Years back I was playing with the idea of making a bay boat out of it and made some sketches. Here's one:
Image

Shown with an armstrong type bracket. I love the versatility that comes with these: opens cockpit space, easy entry from the water. But it really screws up the docking maneuvering for a small boat. Cg offset can be at least somewhat compensated up front if you plan ahead. As shown I used a shorter bracket and notched the transom for hood clearance, in order to minimize the moment from the engine.

Salty F17
Active Poster
Active Poster
Posts: 318
Joined: Wed Aug 15, 2018 3:33 pm
Location: LA

Re: OB21 possible?

Post by Salty F17 » Fri Aug 02, 2019 4:24 pm

Matt Gent wrote:
Fri Aug 02, 2019 3:08 pm
Jondavis wrote:
Thu Apr 11, 2019 2:54 pm
I’ve contemplated building a c21 and cutting the sheer down like this but I’m thinking it’s a deeper hull than I’m looking for we do a lot of intracoastal cruising and beach the boats a lot. I have a 22’ very deep vee now and I’m trying to get away from the rock and roll that comes with the deeper boats.
C21 is not a particularly deep-V at all at 12deg, like most boats here. It just has high gunnels with the second topsides panel. It would make a decent bay boat by just omitting the upper panel.

Years back I was playing with the idea of making a bay boat out of it and made some sketches. Here's one:
Image

Shown with an armstrong type bracket. I love the versatility that comes with these: opens cockpit space, easy entry from the water. But it really screws up the docking maneuvering for a small boat. Cg offset can be at least somewhat compensated up front if you plan ahead. As shown I used a shorter bracket and notched the transom for hood clearance, in order to minimize the moment from the engine.
what would be the width of your c21 design with the carolina type shear i see lose a foot in length but how wide is the hull
Check out my build----C17---- hit the link viewtopic.php?f=2&t=63575

TomW1
Very Active Poster
Very Active Poster
Posts: 3076
Joined: Sun Apr 19, 2015 10:57 pm
Location: Bryson City, NC

Re: OB21 possible?

Post by TomW1 » Fri Aug 02, 2019 6:25 pm

I wouldn't worry about the width. It is very wide as is and you might lose 4" at most but you can make the upper deck slightly as, if I remember correctly they are 12" wide, An 8-10 might even look better.
Restored Mirror Dinghy, Bought OD18 built by CL, Westlawn School of Yacht Design courses. LT US Navy 1970-1978

Matt Gent
Active Poster
Active Poster
Posts: 396
Joined: Sat Jan 05, 2008 7:54 am
Location: PSL, FL

Re: OB21 possible?

Post by Matt Gent » Sat Aug 03, 2019 6:28 pm

I didn’t build a 3D model, only the 2d lines shown. The floor/sole would be the same width. I imagine it would lose a couple inches per side, varying by location depending on the flare.

The point is just shear and deck changes can get a very different character of boat while keeping most or all of the structure and performance aspects in place.

Post Reply

Who is online

Users browsing this forum: No registered users and 9 guests