Ok so I'm building a bismarck hull from scratch. I have a decent enough idea about how to make ribs to be abe to get started. I do how ever have a couple of questions: 1) For the ribs about how thick would be good for 3/8" ribs? (meaning thickness from outside moving in) 2) What would be a good size for a keel piece? (i.e. 1/4" or another size) 3) I was thinking because of the size of the ship to use a kind of three keel system meaning I have the main one run down the middle but also have two more (1 on each side of the main) in the wide part of the ship to help with making the hull stronger. Would this be a good idea? Any help would be greatly apperciated
hey there, im curently working on both bismark and tirpitz. for the ribs im going 3/8 thick, and for how wide u want to go its all up to you, just remember there are alot of things going in the boat so dont go to wide. best bet is to order a set of plans from strike models, thats wht i did. if u go to my build thread u will see what i am dueing ( bismark and tirpitz build ) the plans ar genaric so there will be a little bit of tweeking, the plans come with the rib template and where they go on the ship. the template is drawn up for 17 ribs and u need 19 spaced 76mm apart so u wull have to find the center of the ship and go from there when u have your 19 ribs drawn on the side of your hull u will see that only the 3 center ribs will line up sorda lol i will take all 3 ribs #8 from plans and move them to the new spots verry minor. for the rest of them i took the rib template and scetch the new ribs in place. thats where im at right now. just look at my thread u will see exactly what i meen and how great the strike models blue prints are hope that helps
1 - For the inwards thickness of the ribs I probably would go about half an inch, much more and you're probably adding unneeded weight, much less and you may be venturing into the territory of 'too thin'. 2 - See answer to 3, but I like the concept of 3/8" on the larger ships (though I have not built one from wood) 3 - I think a very common practice when wood-building larger ships such as the Bismarck is to use a single piece of plywood as the flat bottom of the hull and join the ribs into it, using keel pieces only fore and aft where the hull is no longer flat.
@Lloyd I have been reading your thread and find it helpful and interesting. I have also purchased the plans from strikemodels but are waiting on them to be delivered. the delay i believe is attributed to what they mentioned about the storage and them moving to seattle. @nick, I was thinking either 1/2" or 3/8' for inward thickness and completely understand what you mean by to thin. as to useing a flat bottom piece instead of a keel wouldnt it be structurally stronger with a keel over flat board or does it not really matter?
From a structural standpoint, I guess that would depend on the strength of the bond / join between rib and bottom / keel. Don't forget the subdeck assembly will link all the ribs together at the top too. Single keel down the middle will give you problems for waterchanneling - you'll either have to build your channel on top of it, which is a less than great plan, or you'll have to cut out a good chunk of it down the center of your hull after you've fiberglassed the bottom. Going with the base-board eliminates the need to remove the keel because there isn't one to remove. The other approach, if you don't want to do a base-board, and really like keels, is a double keel about 2" apart running most of the length, joining with to single keels fore and aft. Instant waterchannel formed by the keels. My Maru (a much smaller ship than the Bismarck) was built this way, you can see pictures if you follow the link in my signature. (After assembly the pieces of ribs between the keels were removed to allow waterflow)
hmmm very true with he water channeling. i hadnt even thought of that. as for the double keel i would end up having basically 4 then with the double main one and then a much smaller single one at the bow and stern.
