mainiac68

Hi all, I'm planking the hull on a 56" tug and am considering a 22cc gas for power. This hull may end up being a plug so the finished hull may be fiberglass. Anyway, I'll need some kind of reversable transmission/gearbox using a servo or solenoid for reverse activation.I would add a starter also to eliminate pull starting. It will be water pump cooled and have anexhaust system as needed.The tug was originally going to be steam but maybe the next one. I've built RC boats; scale, sail and fast electric but I'm not a machinist so I'm looking for an existing product or one that can be modified and adapted to this use, or scratch built if simplified enough for common hand and power tools. Anyone have some ideas?

lslewis

My Feedback: (2)

Solve all your problems go electric. The ESC acts as ur tramsmission giving you forward and reverse. No need for a pull cord, gasoline, lube oil, starting problems...

mfr02

Reversing - Kitchen rudder.

more coffee

Your gonna spend the same on the engine as you will the motor..
your looking at quite a large scale prop. so get a large motor..

Apismelifera

Just out of pure idle curiosity, where will you run it that you can use a gas engine?

I am designing my own at the moment and planning on running mine at one or both of the local parks. Which for me means no IC engines. My concept is for a large AGM battery and twin electric power.

mainiac68

Interesting responses so far. The "Kitchen rudder" might be something I'ld like to use in the future but not this one. The tug is modelled after a LT Army tug. Originally built as steam,this would represent a later configuration after being refitted to diesel.The scale prop will be 3.5 in. or 4 in.(can't remember without looking up) I can fit the performance of the gas engine to the boat by sizing the prop diameter and pitch.I've done electric for 25 years so am quite familiar wiht that whole scene. As this boat was originally built for steam and I have a single and a boiler built by a friend but it is not reversing. Also, steam is a whole different commitment to the model and I have numerous things to build before that.

I am in southwest Florida and am surrounded by water to sail in; ponds, canals, lakes, etc. Organized RC boating is done in many parks and I've only been to a handfull and know three that allow IC. Anyway, I've run weed wacker motors but just in fast hulls, none in scale. I have seen it though and that's why I'm interested. From my limited knowledge of full scale workboats (derived from fishing and lobster boats) I would need a gearbox that is basically in/out and reversing. Conveniently the gas motor is clutched so that problem is taken care of. So, discounting electric completely........any ideas?

areseaer

What about gas/electric like trains and some larger boats use with diesel/electric. Just need a switch to reverse polarity for reverse. might take some trial and error to find what would work good. May need to look at that for my fishing boat project. would be real cool to have the smoke and sound of a real engine. Backup electric power if the engine stalls might be a good idea too.

Kmot

My Feedback: (24)

If I were going to use a gasoline engine, I would look for a four stroke version instead of the ubiquitous 2-stroke. Less noise, no smoke, much, much more pleasant exhaust note. In Kalifornia, most if not all by now, power equipment has been mandated to be four cycle engine powered. So there are tons of four strokes to choose from. Keep the built in fan and shroud and you don't need to deal with water cooling.

mainiac68

Hey, KMOT, that's very good idea. I had not considered that these engines would be four stroke but that would be waaay better for all your reasons. I'll have to check here for availability but I think they are all still 2strokes. I have located info on a reverse gear that would work and the typical clutch on these engines would probably have to be reworked to engage at a lower rpm. The 4strokes idle better in the new machines? Thanks for the info.

mainiac68

Hey Areseaer, thanks for the idea but read my post to KMOT. A four stroke engine sounds like it could be tamed to give the operation approaching scale idle, sound, etc. The planning phase continues.

Kmot

My Feedback: (24)

Let me locate the thread posted on another forum, where a father and son team converted a four stroke power equipment engine for use in their big model boat. Video and all. Sounds awesome. I will find it and report back.

Kmot

My Feedback: (24)

Found it!

http://www.rcgroups.com/forums/showt...t=sound+awesom

And I was mistaken, it is a 2-stroke with a modified exhaust.

More on the boat and engine:

http://www.rcgroups.com/forums/showthread.php?t=1240737

Kmot

My Feedback: (24)

I still think a four cycle would be the way to go. I did a Google search for "four cycle string trimmer" and tons of hits come up. There are many available, in the 25 to 30cc size. Brand new string trimmers are around $175 for a Troy-Built, and up, but refurbished Ryobi four cycle string trimmers are $95 bucks. That's not a bad price for a 29cc four stroke engine. Maybe you could put a brushless motor on the string trimmer and still whack weeds with it.

mainiac68

Thanks Tom, I will do some research on four stroke machines. The idea is that the engine must idle slow and when operating I don't want to hear engine noise just exhaust noise. The engine will be reduced to bare essentials ( no cowling etc and will be redesigned for electric start) That boat looks GREAT! We used to water cool DIY before all that was popular but I've never done a Ryobi. The others we just left the top cooling fin on the head, took out all but the bottom one, made a jacket of thin aluminum and wrapped it. We used JB Weld to fasten and seal edges and inserted tubes for in/out. No fancy machine work required. Yes it sounds crude but you can do a good job and most importantly it works great. I will have an electric pump for cooling and a fan if needed. The 56" hul has loads of room and can carry lots of weight. It is a tug after all. Fred

mainiac68

I found the Troybilt 4 cycle trimmer online and it takes the electric start accessory. Not sure if that will be useable in it's present form but I plan to go to Lowes to see if they have one in stock for a closer look.

Kmot

My Feedback: (24)

Did you see anything at Lowe's?

mainiac68

Going Monday. Saturday was wife day and this Sunday had church duties. Will let you know tomorrow.

cyclops2

I have built a 96" WW II PTB.

Tried a 55 cc chainsaw engine with a clutch. Used but good. It turned out to be a REAL DOG. The engine could NOT be coupled EASILY to any available transmissions.

Went with a Minn Kota 45 pound thrust trolling motor.......1 to 2 step up timing belt drive to get a good top speed. Novak Reversing Super Rooster ESC rated for 60 amps. Does handel connecting a large car battery to it with reversed terminals.. couple of times.

2....Prop shop ...England .....5 bladed props ...4.5" x 4.5"

Added a synchronized engine exhaust sound system with a 120 watt dual channel amplifier & 8 Caddilac speakers.

Pirece of cake & runs perfect.

mainiac68

WOW! 96" PTB-nice! Do you have any pics posted somewhere? I only have 56" to work with but am looking for power but not speed so gear ratio could enter in. The trolling motor doesn't overheat running out of water? Look forward to pics.

mainiac68

Kmot

My Feedback: (24)

$97 at Amazon:

http://www.amazon.com/Reconditioned-.../dp/B00339TZWE

$70 at fleabay:

http://compare.ebay.com/like/3505698..._lwgsi=y&cbt=y

Tidnab

My Feedback: (51)

I saw a Troy Bilt 4 stroke trimmer at a yard sale near me for sale that had a grey housing. It was $20,but said on it that it wouldn't start.Are you good at fixing ?

mainiac68

Never seen a Troybilt with a grey cover and I've never been inside a 4cycle trimmer engine. BUT, you can fix most everything if it's worth it.

mainiac68

Thanks for the info. Looks like this is getting easier and cheaper by the minute. This is going to be interesting. I'll keep you informed as to how it goes. !st get it. Then start it to make sure it runs OK. Then strip down to (A) get it ready for marine use and (B) start planning for electric start. I know that the electric start willadd work, parts and pieces but but you know how it is when you want what you want . Thanks again

Fred

mainiac68

Hey Tom. I read something interesting on a review from the Fleabay link. Because the unit has an "oil pan" sort of, it can only run safely at a certain range of angles. I'll have to go back to Home Depot and take a closer look to see if I can tell if I can lay it down enough to sit in the hull correctly. If not then maybe modify the base to make it work.