GATO! (It has begun)

[matthewnimmo]

Thanks again! Looking forward to getting it in the sub:)

[matthewnimmo]

While awaiting a new LPB ive been building my storage container. Nearly done with it. Just a few more adjustments to the top and cutting out the vent holes. Then ill fit it with some foam

[matthewnimmo]

Tomorrow (i've already measure the tub and i think i can do this crossways lol) after i finish my box, i'm going to try to get the weights right with my sub in the bathtub. So silly newbie question, whenever one starts off with his sub in the water is there a method one should go through (for example, do i need to rock the sub back and forth in the water some or push it down some) or do i simply just put it in the water and go bananas? I know this sounds so simple, but its funny how this has never really came up before (or at least no were that i've looked). Sure, you read the pre launch check list items; but this is different.

Thoughts?

[He Who Shall Not Be Named]

Initial trim; the establishment of amounts and location of fixed lead ballast and buoyant foam:

1. Establish submerged trim. With the SD's vent valve open (recommend the SD power switch be off, you wont' be doing anything with the SD other than permitting its ballast tank to flood) place the maximum amount of fixed ballast weight as low as possible in the hull that the maximum amount of foam (as high as possible without topping over the designed waterline) will permit with the boat assuming neutral trim.

2. Establish surface trim. With the SD's vent valve shut (again, the SD's power switch off, and the ballast tank dry) observe the relationship between where the model actually floats and the designed waterline -- the boat should have too high a freeboard (vertical distance between deck and waterline). Move foam vertically (above the designed waterline) till the boats designed waterline falls along the plane of the actual waterline.

Done.

Leave me alone!

(nice box, by the way).

M

[trout]

I still remember putting my Gato in the tub and naively thinking it would sit upright. It flopped on its side and kinda looked like it died. As far as shaking, not violent, but just to see if more air would come out and tap water has bubbles in it that will cling to the sub. So, gentle rocking and/or running hands along the hull will dislodge a majority of the air. Then follow what David said submerged first then surface trim. You are almost there. This can be a very frustrating time on the Gato, so take breaks and walk away if needed.

[matthewnimmo]

Initial trim; the establishment of amounts and location of fixed lead ballast and buoyant foam:

1. Establish submerged trim. With the SD's vent valve open (recommend the SD power switch be off, you wont' be doing anything with the SD other than permitting its ballast tank to flood) place the maximum amount of fixed ballast weight as low as possible in the hull that the maximum amount of foam (as high as possible without topping over the designed waterline) will permit with the boat assuming neutral trim.

2. Establish surface trim. With the SD's vent valve shut (again, the SD's power switch off, and the ballast tank dry) observe the relationship between where the model actually floats and the designed waterline -- the boat should have too high a freeboard (vertical distance between deck and waterline). Move foam vertically (above the designed waterline) till the boats designed waterline falls along the plane of the actual waterline.

Done.

Leave me alone!

(nice box, by the way).

M

lol thanks David!

question about submerged trim: i believe i know the answer to this but im looking for best practice as i dont believe that i want my gato to sink like a rock when the ballast tank is full of water. How submerged should my gato be when the ballast tank is completely full of water?

[He Who Shall Not Be Named]

lol thanks David!

question about submerged trim: i believe i know the answer to this but im looking for best practice as i dont believe that i want my gato to sink like a rock when the ballast tank is full of water. How submerged should my gato be when the ballast tank is completely full of water?

A reasonable follow-up question. An issue I should have addressed during that last screed. You escape my wrath.

As you first placed the weight in the keel, it indeed will sink like a rock (all this with a full ballast tank). You keep adding trial amounts of foam to the outside of the hull with rubber bands till the buoyant force slightly exceeds the gravitational force of the fixed ballast weight. The ideal condition of the boat in submerged trim is this: about one inch of the sail should sticking out of the water, and the boat at a zero pitch angle. All the foam will be placed as high as possible, the top of the foam pieces level with the models designed waterline. Of course you move the foam longitudinally until the boats sits at a zero pitch angle. Once this condition has been achieved (in submerged trim with the boat resting level and with only an inch of sail sticking into the air), yank the thing out of the water and RTV the foam (yes, it will have to be cut up, contoured and what-not) within the hull, girdling the SD.

Then proceed with establishing surfaced trim. See above screed.

Keep that good humor, Matt. It will get you through this very trying phase of the assembly.

M

[matthewnimmo]

Thanks again David for all your help as well as the many others on these forums! I see the finish line... Very close:)

[He Who Shall Not Be Named]

Thanks again David for all your help as well as the many others on these forums! I see the finish line... Very close:)

Excellent. You'll make it. Keep chugging.

M

[matthewnimmo]

@David: I know you're super busy, but did you get a chance to send out that LPB? I'm itching to get this trim done .... thought i could get by with limping along this LPB, but it works for a bit, then i have to take the unit out and fiddle with the pump (by taking a small screw driver and assisting the motor were the plate meshes with it) until it works again. That only last for maybe one rise.

Thanks again!

[He Who Shall Not Be Named]

Sorry about the delay, but your LPB (and other stuff I have promised other guys) gets out of here either today or Monday -- been all balled up trying to get an ID for my Granddaughter this past week.

M

[matthewnimmo]

David, thank you for the new LBP!

My second trim voyage at the pool report-

1). I believe i have a good submerge and possibly surface trim. When ballast tank is ful the sail is about halfway visible (i might be able to do a littlemore but seems thats the tipping point for me as any more weight and she fully sinks never to return it seems (even when engaging the LBP)

2). I might have to work on the surface trim a little more as she tends to tip from side to side until it gets a little bit of water saturated in the hull then she sits up perfect

3). I still notice water in the battery compartment but only after using the LBP (granted majority of those times were when i was trying to get her to surface after taking on too much water during trimming). Perhaps im using the LBP incorrectly? I tend to engage it when im wanting a little more help breaking the surface. Then when i hit the surface i keep it running for a few seconds (ever once in a while ill here the pump bog down and girgle if its too deep it seems?)

4). Bow planes need some work. The retracts seem to be very sensitive and stick alot. If they are not fully engaged i cannot get my full range of motion for the diving

5). My magnets (even the ones that dont have current through them get corroded)

6). Lights, the magnets that handle the light current still need more RTV it seems. After a while they start to pull away from the unit that has them attached via RTV. Also, interesting behavior with them (probably due to the connection degregation of corriosion and RTV strenght failing) when turning on the unit after sitting for a bit all the lights stay on no matter what direction my switch says. Now after i fiddle with the failing magnet connections they resume normal functions

i plan on Rtving the weights and foam to the sub from my good triming results as of last nights pool activities

[He Who Shall Not Be Named]

1. The SAS (of which the LPB is only the pump that discharges either outside air or SD air into the ballast tank) should bring the boat back to the surface no matter what. Are you using it correctly? Are you insuring that the entire sail broaches to admit outside air (as the snorkel induction head-valve opens with a pronounced 'sluuurrrrp!') to break the vacuum whenever the SAS is used submerged or semi-submerged? I think you're letting the vacuum within the SD accumulate instead of breaking it with each cycle of the SAS with the model submerged or semi-submerged.

2. More fixed ballast weight low. More buoyant foam high. You need to increase the metacentric height (vertical distance between the C.G and C.B.). This will cure or midigate the listing as you go from submerged to surface trim.

3. If you permit the model to roll in excess of 45-degrees, both the snorkel head-valve and safety float-valve will unseat, providing a flood path from sea to the forward (battery) compartment. Wa-wa gets in. Also (and this is in the pre-mission instruction -- you do read and follow those .... right?) the pre-mission checks call for you to insure that the snorkel induction-valve is working properly. Is it?

4. Yeah, that retract mechanism is a ***** to dial in. But, once working, it stays working. Here is what I think is happening to you: If you use a switch on the transmitter the 'snapping' action of the retract/deploy servo will be so quick that the immersed planes will water hammer the linkage, and the magnets will part (as they should). Put the retract servo on a dialed channel so you can slowly retract/deploy the planes and avoid water hammering the linkage. Here's a clue: If the planes retract/deploy mechanism works on the bench but not in the water, then water hammering is the issue, not a bad linkage. Another fix is to use the toggle switch at the transmitter, but to put one of those neat little aircraft-gear-door-retarders between the receiver and retract/deploy servo -- that circuit works to slow the servo down -- it will still function to travel to the commanded position, but not at a lightening quick pace. It's retarded!

5. You chip the plating on these magnets and they quickly disintegrate on you.

6. Electrolysis is killing those magnets -- wrong application. You put an electrical potential across them in an electrolyte and it's 'Mr. Science' time. That plating gets ionized, develops the green-crud, shrugs off, and your magnets turn to black poop.

Having fun yet?

M

[matthewnimmo]

1). I have never gotten the sub to return to me after full sinking and engaging the pump (hence why im affraid to add anymore weight to it). And if im honest, i am a little affraid that ill burn out the pump trying (but maybe im just being chicken). How long should i engage the pump for becore giving up all hope that the sub is going to return to me? If the sub doesnt fully sink and i engage the pump it does come back to the surface ( i should have specified that point) now i dont hear a sluurrrp but im usually still using the pump probably by the time the sail has reached the level to make that sound (is it a bad thing to use the pump while the sub is surfaced (but not full surfaced) to bring it up another inch or two?

2). I might be ok with this. Ill see what happens after these weights and foam are dried with RTV. But i know one thing i only ended up using half the weights that came in the kit and all of the foam. Most of the foam is in the back while most of the weight is towrds the front (well the weight is still on the very bottom of the sub but closer forward than aft). Id love to get it trimmed so that fully submerged only a few inches of the tower are showning but i still have that "sinking sub that never returns problem." But it sounds like i just need to keep playing with it. I also noticed in the weight and foam kit there is a strip of lead?? Im guessing i can kut that up as needed for placement. Isnt that bad to have open lead like that in water? Do i need to cover it before using it?

3). You know, i think that "might explain the water in the battery area. Remember how i said she would list from side to side? Good chance it was too much listing. I should have followed the pre checklist clsely last night. Ill do so better in the future for sure!

4). Yeah i think ill just have to keep fiddling with it. But sometimes the binding is at the retract mech itself ( not sure how lose the unit gears are suppose to be but every on e in a while they will just bind up). I might try the idea of moving that action to dial instead of using a switch

5). Bummer, so overtime ill just have to replace them:(

6). I was affraid of that. But to be honest it isnt anymore corrosion than what im seeing on the magnets that dont have a current going through them (but perhaps thats because im in a pool and not a lake at the moment). Do you have a suggestion on a better lighting approach? Im using the magnets that attach the tower to the upper hull as a conductor as well to the lights on the sail (those are holding up nicely it seems)

[matthewnimmo]

Anymore feedback from aanyone on these points? Specifically 1,2, and 6? By the way. Happy Easter everyone!:)