My first build, and I need help!

[beeryboats]

I've just finished all the DVD's and have answered some of my own questions. Like, "What's the tire valve for on the battery compartment for?". By the way David, Mike does a pretty good job there at the end! I still have a couple unanswered questions. You admit in the video that the fore plane retract linkage is the most difficult part of the rig, but you never even show how it works. And you never mention the air snort. And I'm really in the dark as far as sub drive location. You mention that the forward end cap on the sub driver has to be sanded down a bit to fit, then Mike measured the dog bone shafts at 3" total length. That would put the driver in two different places. I know from a past failure this is pretty important.

Thanks,
Jay

P.S. After digging around for the allen wrenches to take the prop shafts out, I came accross a Dremel tool saw. Arrrg! I could have made a much nicer cut on the hull.

[beeryboats]

I'm having some luck with fine tuning the hull/deck joint with filler then scribing the seam just before it hardens. Tricky business. After watching all the DVD's and talking with another bubble head, I'm still in the dark over all the foam and lead needed to ballast the boat. It looks like the same Catch 22 situation I got into with my Type IV I started 20 years ago. I know you need to add weight to the point of just barely bouyant. And if the ballast chamber is large enough and below the water line, once empty the boat should be at the water line. Now I understand you may need to fine tune the fore and aft or side to side level of the boat. Why all the foam in the boat? Seems all that does is make you add more lead to submerge and then leads you to a larger bouyancy tank, etc, etc....

Can anyone chime in here and explain where it all ends?
Thanks,
Jay

[Albion]

My first attempt at a WTC used the concept you are describing, why all the foam and lead (scratch head). The problem is that you dont create a good metacentric height (diff in bouyancy between the top and the bottom of the hull). Mine was a single screw Nuke, and would twitch every time power was applied. Twin contra rotating screw WW2 boats wont be so bad, but you might turn turtle when you empty the ballast tank

[He Who Shall Not Be Named]

You need the lead to make the boat statically stable about the roll (and to a much, much smaller extent, pitch) axis.

Lowering the vertical component of the c.g. increases the distance from the boats center of buoyancy; the metacentric height. The lower the c.g. the greater the metacentric height, the more stable the boat.

All that weight has to be counteracted by buoyant foam, placed as high as possible, raising the center of buoyancy.

David

[beeryboats]

I just found David's beginners info page and read ( and printed ) the ballasting procedure. It sounds like lots of lead down low and then lots of foam just below the water line to counter act the lead. Then hope the ballast tank gets you back to the waterline. Long story short. Seems to me the best place for the lead would be under the ballast tank and therefore the CG, and the only place available for the foam would be fore and aft. Sound reasonable?

[beeryboats]

David, while you're online, can you explain or point me to the right place to see more of the fore planes retract linkage?

Jay

[beeryboats]

Ok, this is starting to make sense. As long as the lead and foam are both below the water line, and they counter act each other in weight vs. bouyancy, a set amount of ballast tank will raise a set amount of upper decks weight (aka displaced water) above the water. So the name of the game is to keep the upper decks as light as possible. And the more room you have for foam and lead you have the more stable a sub you will have. Within limits. So what kind of foam is acceptable?

Jay

[He Who Shall Not Be Named]

Ok, this is starting to make sense. As long as the lead and foam are both below the water line, and they counter act each other in weight vs. bouyancy, a set amount of ballast tank will raise a set amount of upper decks weight (aka displaced water) above the water. So the name of the game is to keep the upper decks as light as possible. And the more room you have for foam and lead you have the more stable a sub you will have. Within limits. So what kind of foam is acceptable?

Jay

Closed-cell type foam. The 'blue' or the 'pink' stuff used as building insulation. NOT the 'white' stuff, it's open-cell and will water-log over time.

Here are some retract mechanism photos for you:

[Kazzer]

Owens Corning Foamular F-250 2 in. x 48 in. x 8 ft. Scored Squared Edge Foam

[beeryboats]

Good deal, I have a half sheet of the pink stuff. Am I correct in my understanding of the ballasting theory? The photo to the right of the actuator arm is what I'm after. Does anyone have a photo or two of the assembled rear of the sub driver?

Happy Turkey Day!
Jay

[trout]

Jay,
Have you seen this? http://forum.sub-driver.com/showthre...ection-details Has photos of the connections.
Peace,
Tom

[beeryboats]

Aha! Now I see the pivot point. Is that a solid aluminum rod forward to the retract mechanism?

My bag of "what the #$@% is that for" is getting smaller. I still have a bunch of trianglular parts and some big bits that look like torpedo stuff left over. The hull/deck joint is starting to drive me nuts. Just a learning curve I guess. After reading what's available on the snort, it looks like I have to drill a small hole on top of the ballast tank for the manifold and glue it in place. I'm not quite sure how the other manifold will glue to the aft bulkhead of the sub driver. Thanks to my Southern friend, I have some idea where the driver goes and it will need to be sanded down at the fore end.

[trout]

I believe it is a hollow tube and not a solid rod.

[beeryboats]

Here's one of the photos on the link you posted. It sure looks solid to me. Or it has some sort of filler at the end.
Jay

[He Who Shall Not Be Named]

It's a hollow aluminum tube (as is the bow plane pushrod next to it). It's vital to keep the above waterline stuff as light weight as possible, hence, the aluminum tube. I cap the ends to keep the tube water tight. If you don't, as it slowly fills with water it will goof up your carefully set submerged trim.

David