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[polycell]

So whats new?
Right I have battled with the free flood holes on my Sheerline type VII and got them finished.  I think I have a design for my ballast tank, just need to do some pre fit trials with tank pump(s) and valves etc to see how it performs. So now a dopey question sprang to mind.  The Sheerline type VII like a lot of boats comes in two in two halves hull and casing so how have you sub build old timers managed to attach hull to casing simplistically so one get to the guts of the boat as required.
Yes OK i could go for thru boat bolts, bit Heath Robinson so.................
Any advice reccommendation(s) would be appreciated TA

[Desi]

Hi,

I assume the hull and casing are separated  at the waterline.

I used 2 pieces of brass tubing, that slide over each other... for alignment to the front end of the boat.
I set the large dia piece at the front of the bottom half of the boat at an angle protruding out a bit above the waterline... and the other brass tubing to the casing, aligning it perfectly in the front. For the back I used a screw on the casing that attaches the back end of the boat!

This system works very well!!!

[6705russell]

Polycell, if you look at my thread from a while back you can just see how the two halves fix together,the bow as a plate fixed in the lower half and a wedge fitted in the upper half to slide under then the rear as a 4mm stud fixed at the rear in the lower half with a hole drilled in the upper half so when joined just screw a 4mm nut onto the post...


http://www.modelboatmayhem.co.uk/forum/index.php?topic=13297.0



Russ

[polycell]

Thanks Russ.  Just one thing, this 4mm brass nut, how did you disguse it?
Was this method of securing the casing to the hull what was recommended by the Sheerline type VII manufacturer?
Fred

[Desi]

Fred,
The sketch should clarify my explanation!

[AKULA]

Hi, look at these photos I found on some forum. You can also use magnets.



Greetings

[sheerline]

The old type7 hull was usually fixed this a lipped locating plate t the front, when the upper hull was placed on the lower hull it is slid forward so the plate in the upper half hooked under the plate in the lower half. The aft end was fixed with a nut screwed down onto a threaded post which was fixed to the lower hull and projected through the deck.

Here is a modification and more suitable method which is employed on the Type2D:

Mount a plate in the bow of the upper and lower hull halves. Make a brass pin which will be fixed into the lower hull plate and enable it to locate in a hole in the upper plate. Perform a similar act at the aft end of the boat. This will allow the hull halves to locate fully.

A method for holding the top half to the lower hull:
If your dive unit is cylindrical, make a strap which goes around the central tank. make  brass block wiith a vertical brass post long enough to arrive somewhere just under the tower and drill thread the top of the post to accept an M3 bolt. Solder the brass block to the top of the dive unit strap with your post vertical. If you drill through the tower deck, the screw will engage with the hole in the vertical post once it has been alinged. The strap on the dive unit can now be tightened and when the top is placed on the boat, it should be permanently aligned. When the screw is located and tightened sufficiently, it will pull the two halves together. This method works and will prevent a gap appearing between the upper and lower hull halves. The screw in the tower can be disguised underneath a lifting hatchway so there is no evidence of how the top is fixed down.

I hope this helps.
Chris

[polycell]

Thanks all, good stuff.  It got the stuff working in the head and now I have come up with a couple of ideas of my own.
One being make up some  (four to be exact) inverted 'L' shaped brakets attach these on the inside hull directly underneath the bollard positions on the casing.  On the inside of the casing under the bollard positions (two aft port & starboard) and two forward again port and starboard, make a half inch or so of  filler.  When the filler has gone off drill a hole thru the bollard position and the filler big enough to take a 3 or 4 mm bolt continue the hole thru the inverted 'L' shaped brakets.  On the casing open up the hole(s) suffiently to take the head of the bolt (cheese headed bolt) so the bolt head when in situ is slightly below the deck line on the casing. On the under side of the each 'L' shaped brackets afix with  araldite a 3mm or 4mm nut so that the bolts can pull down the casing onto the hull. 
Yet to be tried !!!  But thats what its all about, ain't it??    

[sheerline]

One small point, I don't recommend araldite (epoxy) on a sub, it doesn't seem to like subs and comes apart. Certainly don't bond anything to the hull with epoxy... it will definately detatch eventually. I have seen a lot of subs with bits falling apart using this stuff.
I bet a few people will take me to task on this one, but I'm going by my own experience... and that of others!
Chris

[polycell]

Thanks Chriss noted.