OS FS30 marine conversion

That's beautiful equipment. All of it. I'd like to see it on the water.
Rusty

Great job Jim, and a nice boat!!

1/2A Nut wrote:Most excellent Jim, a well earned greenie for you sir!!
What size prop will you test with?
Did you weight the flywheel?
Please post a vid when ready to give it a go.

Flywheel is about 4.5oz. I found a CNC stainless prop at Toledo last year and will give it a try. Not sure of pitch but looks like 45mm diameter. I use a pitch pipe to estimate rpms when on the water. Hope to get some sort of a video up in a couple of weeks or so.

I have a 4 stroke setting on my audio Doppler app will post the reading of your best vid pass
you can compare to the pitch pipe reading.

With that much flywheel weight it should hold a very solid NV setting and able to idle down
under prop load for easy launch and docking. Your lathe work with the flywheel and cooling
ring is fantastic you should have a solid runner with some pep. I bet it hits a good clip of speed.

I finished my rigger design with the Saito SH .30 will be posting a vid soon too here are a few
pics of the completed project:

What did you do to cool that Saito? I have a Saito 30 but couldn't see an easy way to fit a jacket to it. Or are you relying on air cooling alone. It's hard to see detail on a black Saito crankcase.
I've enjoyed watching all or your videos, particularly the ones with the 0.010's.
This latest hydro looks lovely and I look forward to seeing what sort of mph it will achieve.

706jim wrote:What did you do to cool that Saito? I have a Saito 30 but couldn't see an easy way to fit a jacket to it. Or are you relying on air cooling alone. It's hard to see detail on a black Saito crankcase.
I've enjoyed watching all or your videos, particularly the ones with the 0.010's.
This latest hydro looks lovely and I look forward to seeing what sort of mph it will achieve.

Earlier posts show a fabricated water jacket.

I do not have a cooling jacket installed.
To combat heat you can see from the front view the engine is very well ventilated.
I will be using 20% synthetic oil and 40% nitro to aid in additional cooling.

Additional forced air cooling if needed:
Also may use dual bearing brushless 2 wire 60mm computer fan to blow 15 CFM at 7.2v
simple switch on prior to starting. Mainly for when the rigger is going through start up, launch
and cool down phases. Will have water proofing spray over the circuit board.

To water cool:
With fins removed you can cool the hot zone where the piston ring is rubbing.
It won't be easy though the square bolted down footing for the cylinder makes
it impossible to just slide on a press fitted water cooling collar. The up side is
from the footing up to the intake can have an aluminum cooling coil rapped around
70% of the cylinder case.

To Note:
The fastest .12 two stroke rigger in the world does 103 mph uses 70% nitro and must have no
water cooling nor any head fins to stay hot enough to produce top power. The tuned
pipe is rapped in silicon insulation to keep a constant temp protected from water spray
and air cooling.

I have a gallon of 20/60 if I want to cool it more with nitro, I will have a batch on tap
the day I test if I feel the running temps are too much. I have a 40a muffler on the engine
to help it breath better and thus cool better. During bench tests it made more power than the
stock muffler.

Jim how do you start yours with a electric starter or pull cord? I had to use 24v to start mine
the load is very high trying to turn over a 4 stroke.

It's skinny but has a good displacement here is a water test pic to check for leaks and draft.
Engine is well in the clear from water.

Back in 1974 Flying Models magazine had a few pages on model boating every issue. A rigger with a Schneurle 40 hit 74mph which I was very impressed with. To hear that a 2cc boat can go over 100 is most impressive.
I use a standard Sullivan starter and sewing machine belt to start the engine just using a 12 volt battery. In fact, I ran my Trojan F31 (powered with the OS40 four stroke) and while starting it, the belt slipped off the flywheel onto the knurled universal and kept cranking without any problem until the engine fired up.
I'm really looking forward to running the nearly flat bottomed boat once again. It cornered so much nicer than the deep V's that I ran later.
I really want to see how your Saito outrigger performs. I'm sure it will be a lot faster than my Ski Daddle.
But your's has probably not roared up the fjords of Isle Royale either!

Lol mine has only seen a bath tub thus far will post a vid when I get to testing.

I have two starters one a Sulivan the other a Hanger 9 both are in new condition as
far as use very little use. Perhaps when the Saito gets broken in the compression
will be bit less for now only 24v will start it. The engine has been bench tested with
3 props perhaps 8oz total time.

Here is a vid that was shared yesterday to me
vintage O.S. 40FS marine engine


:



- Best no load 16,142 rpm
- Best pass hit 14,211 rpm
- Hit 13,740 rpm 3 times

I would imagine he was using at least 15% nitro the vintage 40 did
not have any trouble turning over with the starter most likely on 12v.
Perhaps with a solid straight line pass it might get to 16.5k ish good info to know.

Prather 245 prop 1.6 x 1.772" for 2.8352" / 72.01mm pitch
Best pass at 20% slip was around 30 mph.
Per:
https://model-boats.com/rc/calc/

That was a neat video. I never figured you could get that sort of speed out of the FS40 being rated at only 0.5hp. It really is a lot of fun to take one of these boats out with a chase boat where you can literally drive for miles instead of just going in circles. A nice 20-25mph boat is good for this (not a 100mph rigger!)
It looks like the owner was able to rig up dual exhausts on his boat. A look at the engine installation would be interesting.

Yes his efforts reminds us of what good ole torque can do. As you can imagine his
dual exhaust system must be adding additional back pressure but with a unique sound
effect. Rare to find a vid where the boat was set up to go for some performance when
it comes to 4 strokes. Most are in scale jobs for just cruising around. Good base line
to understand what works prop and rpm wise in sport running mode.

I would have guessed the duals reduced back pressure. I love the sound at idle, kind of like a cammed up car engine.
There's no arguing the craftwork that goes into boat building.
Good stuff.
Rusty

Great thread guys.

Great looking Boat guys and the vid was cool to watch ,, Makes me want one , Thanks !!

Did a test hit at the big pond today I was under propped here is the experience.
Will post another vid once everything is sorted out.




 Published on Jun 10, 2017

First launch with the  Saito .30  
Octura 1637 prop.
Unloading after the launch and gets up to 15,665 rpm then falls off the prop
out in the rough water unable to maintain it's bite.
Speed wise it got up to a brief 31 mph then fades off and completely bogs down after the turn.

Tom a club member did a great job launching the rigger:



Pic of the rigger getting back from it's boat ride notice the prop size was a bit too small for a .30
Will get a vid with the right prop soon. Was playing it safe with the engine loading since the it is not water cooled seemed to do ok though, but gets very hot if not moving on the water.

While attempting to make a video of my Ski Daddle, I found that the engine had a broken intake valve spring. I replaced it with a similar spring and hope to try it again today. Engine would run fine and then just randomly quit at any throttle setting.

Wow have never heard of a spring breaking they sure get a work out no doubt.
Look forward to seeing what prop worked best with your .30 powered mono.

https://www.youtube.com/watch?v=Ong8vvmBY14

https://www.youtube.com/watch?v=B8sSV8M8Xu4

Prop is not optimized, but finally got her running after fiddling with the carb and fuel lines. The engine seems to run just fine with my junk box replacement intake valve spring which I found in a box of parts retrieved from the city dump. The previous owner would have been proud to know one of his treasures ended up recycled in a model boat!
The water jacket works great with the engine cool enough to touch after a high speed run. The passage around the block isn't nearly as large as found on the FS40 and FS48 done previously.
I hope to post a travelling video taken from a moving boat sometime in the next few days.

Best peak hit 9,043 rpm, I enjoyed all 3 vid posts sounded awesome mang,
greenie for sharing thank you Jim!


Time to get a 1080p sports cam clipped to the ball cap, they are cheap these days,
will make for some nice clear vid of you 44yr old mahogany baby!!!

Do you guys typically crank the engines with the glowplug loosened? I've seen other videos where after it's running, he takes a wrench and snugs the plug.
Rusty

Hi Rusty if you watch my vid that's exactly what I did

Love the Vid. Jim ! you were having some fun when you turned and looked after doing that donut the smile is priceless . Seemed to bee tracking in the water well and staying above water

https://www.youtube.com/watch?v=F09SxpdiOuI

Most of the audio on this video is from the little Honda 2hp outboard, but you can hear the OS from time to time.
That little engine just runs forever on a 6oz tank at part throttle.

https://www.youtube.com/watch?v=OUwDwn-G-qM

Running through smaller waves on Superior.