Stuffing/Shaft Resizeing....

[Crash104936221]

Hey

Im slowly gathering info and parts to start building a Tug, ya i know nothing spectacular just somthin i can say i built from scratch

Spec's
40" Length
11 1/2" Beam
4 1/2" Draft
Single Screw/Rudder
FiberGlass Hull and bulkheads

when i go to put the driveline in im not sure as to where the exact location of the motor will be thus hindering my ability to pre aquire all the parts (i hate waiting in the middle on parts)

can i just buy a setup that is longer than i need and cut it down to size? by pulling out one bearing, trim/debure the tube, and re insert the bearing? then just shorten the shaft to lenght on the drive dog end?

is it better to have a short stuffing box or a longer one? what one has a better chance of resisting bending if the prop was to catch a underwater object (ya i know bad word in a boat board lol)

Thanks for your time
Joe

[Hydro Junkie]

The first question I have for you is are you running your stuffing box inside the kiel structure? The reason I ask this is because I'm also building a tug. My stuffing box is simply a 1/4 inch inside diameter copper tube, 12 inches long, sandwiched inside the kiel. My tug is a 1/8th scale yard tug from plans I found in Garden Railroad Magazine. It's 49 inches long, 15 inches wide and draws approx 7 inches. If you do it the same way I am, to complete the stuffing box, you install THREE bushings, one in the middle and one on each end. Fill the stuffing box with grease and you are done. As for length, you want the stuffing box to end as close to the motor/gearbox as possible, leaving room for the other required hardware. This prevents whipping of the shaft, also the reason for installing the center bushing in the stuffing box. As for the shaft, get one which is a little longer than what you think you will need. When you get the power plant location determined, you cut the copper tube to length inside the hull. The outboard end should be installed flush with the outside of the structure. Now install the motor/gearbox and cut the shaft to length. That's all there is to it :)

[Crash104936221]

My Scale is 1/12th
it will be passing through the keel but only for about 2-4" if im not mistaken with about 10-12" inside the hull

the boat was originaly a logging tug in Ottawa, it was then bought and trucked down to the St. Lawrence River, where we live and used for marine construction (dock installs, dredging, and many other things)

thanks for your help
what do you plan to power the boat with? im stil undecided on what to use, im looking at the Graunpler 720 or 900, or i might try salvaging a blower motor or winsheild wiper motor from a parts vehical

Joe

[Hydro Junkie]

Haven't decided yet. As my boat is a larger scale, I will be spinning a 5 inch or larger prop. One thing I do know is that I will need to ballast mine down to get to the waterline. I'm guessing, though, I will be using a 12 volt battery. That way, not all the weight will be just lead ballast. On yours, I would suggest bracing the stuffing box to the inside of the hull. This will prevent the tube from getting bent and/or kinked with 8+ inches inside the hull

[Crash104936221]

ya i am thinking i might take and once its set were its going to reside, i will make a baffle on the motor end and fill it in around the tube with epoxy

im not sure but im guessing my final weight to the water line to be around 40-50 pounds

since the actual tug spins a 4blade 46" x24" prop im hoping to find a 3.75"-4" x 2" prop that i can use

going to use a Hobbico CS-80 servo for the rudder since it masive torque will come in handy (that and its cheap) 334in-oz @6v

Joe

[Hydro Junkie]

There are a couple of places that I know of who sell props like you are looking at. One is shipsnthings.com and the other is harbormodels.com :) They carry different manufacturers for props, so you might want to check them both out. They also carry different parts for outfitting your boat, such as lights, sound units, scale fittings(anchors, detail items), etc. Harbor Models kinda sorta specializes in tugs, where Ships N' Things covers all kinds of ships. Hope this helps too :D

[Crash104936221]

thanks
i have been to Harbor models but i will try out Ships ' Things

Harbor has some good selection that i may end up going with the pitch is a little steep though (not that its realy a problem)

any guesses to the pitch of the Rivabo 4blade 100mm props?

thanks agian
Joe

[Hydro Junkie]

Not a clue, as they don't put out that info :(