1/8 scale chris craft "cooling questions"

[Scott Richard]

I am almost finished with a Dumas barrel back chris craft and would like to install a water cooling jacket for the motor and speed control. The probem is I don't know where to place the water pickup tube on the bottom of the boat. Will it even work on the bottom of the boat? Most race boats will have them hanging off the back, but I would like to keep the scale look of the old chris crafts while being able to have long run times will a cool motor and speed control.

[Hydro Junkie]

Several manufacturers make through the bottom pick ups. You will need to mount one close to the rear, where water is always running along the hull. You will also need to figure out where the water dump will go. It's better to be able to see the dump so you can verify the system is getting cooled

[jbrase2000]

Scott,

Did you work out the water cooling question. I'm working on the same boat so I'm interested in your solution/experiences. I'm thinking it would be cool to drill out the fake exhaust pipe fitting on the transom and dump the water out there if possible.

I'm also thinking I'd like to figure out a way to have the rear deck be removable for access to the rudder linkage. I'm at the point where the instructions tell me to glue the balsa deck block in place so I'm pondering this. It would make planking the rear deck a little more tedious and I'd have to figure out a way to hold it in without gluing it in. Maybe a couple of little pieces of velcro? Do you think this is a good idea or is it not necessary?

John

[Doc]

John,
Can you make the deck removable? Sure, and how well it looks will depend on how you decide to accomplish it. So, the next question is naturally, 'How do I do that?', right? I don't have an exact answer for that but like any other question/problem, breaking it down to 'smaller' steps is usually how you solve it.
1. Has to look right.
2. Has to be easy (maybe 'fairly easy') to remove.
3. Has to be water tight.

Step one means you should follow the building instructions for the deck as closely as possible. Instead of building it on the hull, make a fixture that duplicates the hull and build it on that (or a flat board?). Are there 'deck lines' that can be used for the seam between rear deck and the rest of the deck? Would 'moving' the seam between parts of the deck forward or rearward make it easier? Any deck fittings that could be made to hide that seam, or a hold-down screw, or hinge?
Step two depends a lot on what you decide in step one. Maybe a simple latch and hinge, couple of screws, magnets, how about the 'goo' used to temporarily hold things to a card (no idea what that stuff if or where to get it, but it'd sure be handy!)?
Step three can be done a number of ways (hows that for a 'cop-out'?). 'Best' would be a very close fitting structure (I don't know about you, but I'm not capable of building like that except by accident - lol). A 'compression' fit, bind the deck down tightly, hmm, maybe not so good an idea, or very practical? Use something to seal the deck opening like silicon, grease, or some other water proof 'goo'? Build a 'false deck' under the outer deck using a combing to keep water out?
By this time you've probably figured out that I've never had my hands on a 'Chri-Craft', right? But this is more a 'how to get there', rather than a 'how I did it' thing. Hope it may have helped, or given you an idea or two...
- 'Doc

Scott,
Do a search for "R/C combat". These guys (and gals) have some really nice, small, water pumps that move ~lots~ of water (probably more than required for cooling your motor). No idea as to cost, sorry. Then there's the old windshield washer pumps (best if removed from the wife's car, not yours!). Or, just drop the voltage used to run your motor, or use a diffrent motor (whole new can of worms)...

[Scott Richard]

Hey John (jbrase2000),

Good to hear that there is some interest in old woodies. I can see we're on the same page because that was my whole plan was to dump the water out of two small brass tubes out the back of the boat like exasht just under the water line which at full speed would be seen to insure cooling is successful. After doing this I found you do need a small pump to force the water through the cooling jackets.The boats speed is not strong enough to feed the water through on its own (with 45 deggre cut brass tube). This gave me a idea of finding small air pumps and trying to simulate real exasht bubbles.But I have not been successful in finding quiet enough ones. As of now my chris craft has been on the lake 5 times, and cooling was not effective as I planned. I have been using a RAM product called a bildge pump but using it as a cooling pump. I have smaler ones on order but plan to hook up real exasht bubbles to go along with my RAM running lights. Have fun on your build. But I would be careful with the removable rear. I built this boat for lake tahoe and plan to run it a ton so I would have to go aginst the removabe rear for leaky reasons. I have no problem accessing my rudder and exasht tubes. \

scott

[jbrase2000]

Thanks to Doc and Scott for your replies. Gives me "stuff to think about."

Based on Scott's experience I'll probably forget trying to make the rear hatch removable. I hadn't thought about using a powered pump for water cooling. I'm interested in hearing about how you end up solving this one - so I can copy it.:)

It looks like the barrel back is on the back burner for a couple of weeks due to the work schedule.

John

[rolfs]

Hi all,

I'm looking for a set of batteries and possibly a motor that will give an hour plus of run time for my Barrel Back. Does anyone have any specific suggestions for what works well for this model?

Thanks,

Rolf

[Scott Richard]

I am using two 6 cell 1500 packs, with a 23 turn traxxas boat motor. I can usually get about 23 minutes of run time, I would also like to know a combo that can get good speeds and at least 45 minutes of run time. Anybody? would a 12volt system get better times?I know if I buy good 3300 batterys that would also help but I don't know about 45 minutes to a hour.

[Doc]

Scott,
Run time depends on the amount of current the motor(s) draw and the 'Ahr' capacity of the battery(s). What you should do is perform a 'stall' test on your motor to see what it's maximum current draw is. Dividing that current (from the stall test) into the battery's current rating will tell you how long the motor will run at full speed. 'Real life' circuits are always a bit less efficient than they're supposed to be, so the actual run time will be slightly less than what you figure it will be...
- 'Doc

[Doc]

...Oops, should have put this in the above, just didn't think about it, sorry.

For extended run times, most people just have more than one battery pack. Swapping out batteries is sometimes much easier than trying to squeeze in a larger battery, doesn't affect the boats trim, and you've got one (or more) recharging all the time. Nothing 'earth shattering' about it. Bigger batteries mean less performance to some degree, and too big of'a battery means you gotta submarine...
- 'Doc

[bobsolo]

Hello all, I am thinking of buying this kit for my father for Christmas, and have a question. How loud is the boat with a standard electic motor? My folks live on a lake and have very testy neighbors. I'd love for my dad to be able to build and use the boat, but if it's loud he may not be able to enjoy it as much.

Thanks in advance.

[Scott Richard]

Hey, bobsolo

I have the Chris Craft Barrell Back kit with a 23 turn traxxas boat motor in it. Around 200 feet away from the shore you can't even hear it. Near the shore I can even hear the wake its making over the motor noise. This kit pulls a pretty big wake for its size. (Thats cool!!) I feel you could even get a softer sounding motor because the traxxas motor has a fan cooling it as it runs. But as sounds goes I still would be able to hear the beeping of my speed control working. With some motor lube its even softer sounding. No problems with the noise.

[Doc]

Bob,
An electric boat is seldom as loud as an electric 'weed eater' (before the line hits the grass). Noise really shouldn't be a problem.
- 'Doc

(Most of us 'old farts' can't hear that well anyway!)