bertram31.com

Hi Guys,

A friend of mine runs a B28 and needs some hull drawings. The marina wants him to have a cradle for yard storage. He operates a fab shop, so building the cradle is no issue.. but finding the drawings has proven difficult. Does anyone have the hull drawings for a 28?

Thanks in advance,
Scot

My B31 came with cradle plans. I don't know about the B28 though, but I would bet they came with the same documentation.

I never found either cradle plans or hull plans when I was desperate to find them, too.
There is a one page plan in the owners handbook but I doubt one could create a cradle out of.
If I were to build a cradle I’d visit a 28 with lots of carton boards and scissors, to make 2-3-4 or however many are necessary hull section mock-ups. Then Id take those to my blacksmith.

I did a google search and this popped up on THT

https://cimg2.ibsrv.net/gimg/www.thehul ... 171aa.jpeg

That's the one I was referring to.

Yannis you can build a cradle based upon that drawing if you can read the numbers.

has multiple stations (vertical slices) drawn out, look for a video on lofting, back in the day they would do it on a big floor and mark out dimensions on the floor and connect them with battens to figure out how to make the various components for a hull.

in this case, the image gives you a 1/2" view of the hull at 3 different points, build 3 different cradles and space them out per the drawing.

here's a similar one for the B25- more explicit - tells you cross section and where to put the cradles
https://photos.app.goo.gl/PfomxMgKZjJtYkTa6

daytrip - the guy who built out the tricked out B28 which was made to a CC with twin outboards seems to have modeled the hull, he might be able to share data

https://www.thehulltruth.com/boating-fo ... tch-5.html

Daytrip is a good option, I thought of him as I think he has a 28 Hull CAD drawing. I can’t currently contact him! My PW /email/user name is a mess on THT.. apparently you can’t change emails on that site and get it lined out lol.
Thanks guys

I found that one drawing as well, can’t read and of the dimensions

KTM, Scot,

That's the point; we can't read the numbers on that sketch.
Also, WE DON'T KNOW if the areas (where this sketch positions the cross sections) are good supporting areas for a cradle.

I'd still do it with cardboard, marker, scissors and tape. I'd talk to a naval architect to specify the support areas for me (where and how many).

Short strips of door skin and a hot glue gun also make great templates.

Yannis

That drawing shows right were the supports go. There are three supports. One just forward of where the shafts enter the hull, the next one is supporting the engine weight and it looks like on the 28 that one is under the pilaster and the forward one should be just forward of the sling mark.

Not sure if you can do it but try blowing up the picture and then get a good magnifying glass. That is how I pulled some of the dimensions for the 31.

If you can find someone with an owner's manual in good shape, try looking at the drawing provided in it. That will be much clearer, and you can easily blow that one up on a copy machine.

Tony,

I cant see how you understood the positioning of the three supports, but if you say so...
Additionally, those points were calculated with gassers. I don't know if the extra weight of diesels should change them and how.
That’s why I said a naval architect would be helpful.
The first one who does all that work, may then diffuse the new sketch, dimensions etc. for the rest of us.

I tried everything, even asked my 23yo son to look for me, nothing. This sketch’s remarks must have been written by a doctor!

Yannis

The weight of the engines does not make a difference. The cradle was the same no matter what engines went in. The supports are designed to equally support the boat so it does not crack and to limit twist. The support under the Pilaster supports the engine weight.

ktm_2000 wrote: ↑May 24th, '22, 13:30 here's a similar one for the B25- more explicit - tells you cross section and where to put the cradles
https://photos.app.goo.gl/PfomxMgKZjJtYkTa6

My eyesight is terrible would you have this in a higher resolution image so I can enlarge it. Thank you

Rick,

I am not sure why google doesn't let you zoom in on that, try downloading a copy and opening it up locally.

If that doesn't work for you, my local copy on my PC can be zoomed in on, maybe google is reducing the resolution, I could email you a copy directly.

I appreciate the inputs guys, plenty of neat ideas..however the boat is in the water, should have stated that up front
I think he’s going to pull it, measure it and fabricate the cradle. If the supports are running longitudinal, and well fit to the hull, structural sweet spots shouldn’t matter.

Thanks!

That would be awesome. I did download it but was unable to zoom in clearly.

ktm_2000 wrote: ↑Jun 20th, '22, 14:54 Rick,

I am not sure why google doesn't let you zoom in on that, try downloading a copy and opening it up locally.

If that doesn't work for you, my local copy on my PC can be zoomed in on, maybe google is reducing the resolution, I could email you a copy directly.