Robbe XXI U-2540

[Sonnich]

Hi Guys.

I just bought an untouched new in box robbe XXI :-)

Have a question to those who have assembled one:

I will make this a static diver.
Out of the box, it is a dynamic diver, and it uses 4 large lead bars to ballast it down.

As I want it to have the correct waterline, and im afraid that all that weight is too much ?
I can see in the manual that these bare are installed early in the process, and cant really be accessed later on.

So should I install just 2 of them, or will it be fine with all 4 ?

I have never seen the robbe XXI stock, so I dont know how deep it sits in the water as a dynamic diver, but I can imagine that it is quite low ?

[mike dory]

I have never done a ROBBIE XX1, but a friend and I did do a ROBBIE 212, and they share a few things in common, it looks like it's a vacume form plastic hull that your having to glue togerher. My friend and I found that this made for a very weak joint so we left the lead out and added two brass bars one was on the inside the joined plastic hull the other was one the outside these were screwed together sandwiching the plastic hull between them This did wounders for adding strength to the hull while at the sametime placing the weight at the very bottom of the hull for greater stability. In addition the brass will not corrode as the lead will over time. I believe the brass barrs were 3 ft long 3/4 inch wide and 3/16 thick You could ask Jeff LaRue, to be sure on the measurements, as he is now the owner of the boat. My Best Wishes Mike Dory

[bob_eissler]

All depends on how you ballast it doesn't it? No, really as long as you have enough foam at the water line to compensate, it is all good and the sub will be more stable. I would not use the 2 tubes they give you with the kit since they are placed above the water line and would cause your ballast tank to be too big.

[598602G]

I say splash it and make the molds from it so you can make epoxy glass hulls.

[thor]

Just buy a real scale epoxy glass kit to start with!!!!

[Sonnich]

Thanks for your inputs guys.

Matt, would love to. Have you got a link to one at the same size ?

[thor]

Its close, but not quite the same size. This one is 1/48th Scale.

http://www.precisionpattern.biz/type-xxi/

I've built a Robbe Type XXI for a client. Mike Dory is absolutely correct. The hull joints are very weak. I cleaned the entire surface of the hull interior after the sections were all secured together with acetone. Then, roughed it up with 320 grit and laid up 2 layers of 4oz cloth with epoxy resin the entire length of the hull sides . That really stiffened it up nicely. You'll have to trim some of the plastic parts to fit as this does add about 1/32" of thickness to the hull on the interior.

[598602G]

Matt I didn't know you sell a XXI kit. I am dangerous with some epoxy and glass cloth.