Attaching cross-member to rib

[AviatorJones]

Hey folks,

New here and trying to update the boat my father in law gave us a couple years ago. Been scrolling through some of the build threads here an y'all have some really nice setups! Definitely something to aspire to!

I would like to build a deck from the transom up to where a seat is currently mounted (2nd rib away from transomin pic) to protect/hide the recent electrical work I did. I was thinking of attaching a piece of angle as the cross-member to the rib but can't wrap my head around how to attach the angle to the rib. Does anyone have pics of attaching angle (or should I use square tube?) to a rib for creating a cross-member? I have several ideas in mind but can't wrap my head around what the best method is. I know I'm overthinking it, so looking for some help getting out of analysis paralysis.

Pic of the rib attached below.

Thanks,
CJ

 

[DaleH]

I'd use 1/8" thick 'L'-shaped angle, with a good 1-1/2" leg on each side and would affix to the ribs with good 1/4" high-shear rivets. I can get you the # of them from McMaster-Carr, sold in boxes of 25, they have the same strength rating at the rivets holding the boat together. If you need more holding strength, a block of wood vertical up the rib would give you more surface to affix the block to the tall rib, just don't use PT wood.

 

[DaleH]

Update ... I found some of similar shear value from Jay Cee Rivets, aka www.rivetsonline.com . You WILL need a $30 Haba Freight 'A'-frame rivet tool to properly set them.

 

[AviatorJones]

Wow. Thanks for the detailed response. Bonus points for finding the part numbers.

How do you deal with the space due to the slant of the ribs? Do you just rivet a close to the bottom of the angle as possible and let the cross member stiffen it so it doesn't wiggle side to side? Or is it possible to just bend the lip down to make it level?

Thinking about the gap between the top of the angle and the rib in the pic below. The pic doesn't show it well. Roughly 3/8" gap there with this piece of 1" scrap I had.

 

[DaleH]

With that huge angle difference, perhaps a 'shim' would be best. Buy a heap cutting board at the dollar store, cut out a chunk the width of the rib and length at least as long at the longest leg of the angle ... then figure out a way to cut the angle. But cutting board LDPE (low-density polyethylene) cuts REALLY easy and with a good eye ... you should be able to set the piece in a vice and use a hacksaw or other think kerf saw to cut a few shims.

If the angle isn't as severe, to be honest I don't worry about shims or the angles, I just set the flooring on top and lock it down ...

 

[SaminMass]

Bonus points

That should be Dale’s nickname

 

[Challenger]

If you look at the cross member marked 2 you can see how I attached an angle to the rib.

 

[AviatorJones]

With that huge angle difference, perhaps a 'shim' would be best. Buy a heap cutting board at the dollar store, cut out a chunk the width of the rib and length at least as long at the longest leg of the angle ... then figure out a way to cut the angle. But cutting board LDPE (low-density polyethylene) cuts REALLY easy and with a good eye ... you should be able to set the piece in a vice and use a hacksaw or other think kerf saw to cut a few shims.

If the angle isn't as severe, to be honest I don't worry about shims or the angles, I just set the flooring on top and lock it down ...

Good deal. Thanks again for the info. I knew I was overthinking it. If my f-i-l knew how much effort I was putting into the fine details of this old boat he we would say "It's a crusty old boat - we're not building the Taj Mahalo here.."

 

[AviatorJones]

If you look at the cross member marked 2 you can see how I attached an angle to the rib.

View attachment 115060

Ahh. Interesting. I had though about doing something like that but was worried about the angle trying to twist away from the riveted side. Any issues you've seen with that?

Btw.. It looks like you did exactly what I'm wanting to do at the back of my boat. Any idea how many ft worth of angle you ended up using (ballpark) after all the stringers and legs, etc?

 

[Challenger]

I use 1/8" angle and then cross brace so no worries about twisting, especially when the decking and verticle carpeted pieces go in.

In this picture you can see the cross braces. This is rock solid. You can also see the battery trays I made for my trolling motor batteries.

 

[AviatorJones]

I use 1/8" angle and then cross brace so no worries about twisting, especially when the decking and verticle carpeted pieces go in.

In this picture you can see the cross braces. This is rock solid. You can also see the battery trays I made for my trolling motor batteries.

View attachment 115126

It really looks like you're doing exactly what I want to do. As I was out there today looking over things and taking rough measurements, I was looking at where I could put another bench/storage and move the batteries a little more forward. There is a bench already in place toward the front, but I think I could move it aft to the next set of ribs and still have plenty of room for casting to the side from there, and create a little more room for the front casting deck, in addition to having more storage space in the rear with a new deck there, too. Family of 4 (me, wife, and 11 & 9 y/o boys), so space is getting tight and back-casts are getting contentious, so need to get some space figured out better.