Auto Trim System

[Rick Teskey]

Ever set up your boat in the test tank or pool , have everything running great, get too the pond and have too screw around with you trim?
What about an auto trim system?
An apc chained too a reversing switch too control a reversing gear pump looped too 2 trim tanks one fore and one aft.
When the hull is sitting at water line but still out of trim the apc would send a siginal too ship water fore or aft as needed then the system could be switched off or left on too compensate for spent propel or torpedos or missles .
Sounds simple enough , has anyone tried this?
Rick Teskey

[skip asay]

That's something I've been wanting

That's something I've been wanting to do for years. And how about an ADC-1 controlling a small piston tank located inside the main ballast tank? (see my "Poor Man's Piston Tank Proportional Control" post in R/C Modeler). Put your boat in the water, turn both units on and wait until it settles out. Ah yes, the to try list I have is staggering in size and scope.
Rick -

Here's the way I see your suggestion. First, the APC should control a servo amplifier which then drives the pump. The reason for the servo amplifier is, besides its size, it has almost zero deadband which will go a long way toward eliminating hysteresis. If you use a small enough pump (heavily recommended), the voltage/current needs will not exceed the amplifier's capacity. Then, mount 2 very small tanks only about a foot apart ahead of and behind the main ballast tank. Obviously, that dimension will vary depending on the length of the boat. For trim purposes, only tiny amounts of water have to be shifted and, don't forget, whatever you do shift you must multiply by 2.....making the bow heavier by 1/2 oz. will also make the stern 1/2 oz lighter. Oh, and restrict the size of the tube on 1 end of the pump. Again, we're looking for very small amounts of water. Another reason for that is that, at essentially neutral buoyancy, adding/subtracting just a little bit of weight causes the boat to react sluggishly.

Skip Asay

[Rogue Sub]

I know two people with

I know two people with working ones.
Ctransc (think i spelled that right) on this board has a whole thread talking about it using a weight fixed to a moving track.

Also Rick Galinson had a working set up in his invisible sub at the regatta. It used a pump to transfer ballast between two tanks. Get a copy of the 07 Regatta DVD and you can watch his seminar.

[Guest]

Haven't seen a trim system

Haven't seen a trim system set-up with an APC. Seen trim systems based on a sliding battery pack attached to a servo. Gives proportional control, and it's simple and cheap. One chap has such a system set-up in a small Holland class boat, and another in a larger X-craft. the latter has two trim systems located either side of the centrally mounted ballast tank.

Trimming systems are covered well in Norberts book.

Andy

[robse]

I got that in my SSBN..

Hi

I have a working system in my 1:82 Ohio that corrects a list along the length axis at all times. It does it by adding air to the lowest tank, thus it cannot sink the sub no matter what. (Adding ballast to the highest end might make your boat drop to the sea floor like a leaf in the wind..)
Anyway.. have a look at http://www.robse.dk/pages/SSBN/ElecALT.asp for inspiration.

Note]http://www.subcommittee.com/forum/icon_smile.gif[/img]

[bob_eissler]

Just remember to not allow

Just remember to not allow free flow of air or water between the tanks or all the air will go to the highest and alll the water to the lowest.