The ultimate dinghy outboard

gwozhog

Petty Officer 2nd Class
Joined
Sep 19, 2012
Messages
138
After watching this video I'm now convinced that the 18hp Tohatsu is the greatest outboard ever built for inflatables. My 15hp Yamaha could never plane this many people. This outboard checks in at only 82 pounds so is very portable. Makes me think this engine is probably putting out closer to 25hp.

https://m.youtube.com/watch?v=5ctJNCFInGc
 

Sea Rider

Supreme Mariner
Joined
Sep 20, 2008
Messages
12,345
Some issues.

-Plainly in agreement, Best performer on its own class, superior than any 15 OB of whatever other brand.
-300 CC compared to 420 CC of the 25 HP, so can't be put on same sack.
-That's a Rib, probably impossible to plane if it were a same size SIB. (Tubes poorly inflated issues)
-Probably are using a maximized less prop pitch to plane combo as heavily loaded.
-Current factory delivered niner won't plane out that combo.
-Those Ruskies are very funny, seems all are having fun after drinking some straight shots of Vodka LOL!

Happy Boating
 

Durango318

Seaman
Joined
Jun 12, 2010
Messages
68
I've had a Suzuki df20 for over a year now and so far it's about the best money I've ever spent. It starts so easy, idles nice, so quiet, so powerful, so fast and light weight. The thing sips fuel, the range is incredible. In a 12' RIB with just me, it tops out at 31 mph GPS two way measured. The prop was changed to a 9.25 X 11 aluminum Solas because it would hit the rev limiter. I had to build up a wedge of JB weld on the right side of the skeg to counter the strong tiller torque at speed.
Recently, my son had to sell a new 9.9 Merc bigfoot because it would surge badly at trolling speeds. It was more in the shop than on the water. Mercury management seemed annoyed that someone would want to troll with it. It would not stay working. It was replaced with a new 6 hp Yamaha and it's flawless.
 

Sea Rider

Supreme Mariner
Joined
Sep 20, 2008
Messages
12,345
Durango318 said:
I had to build up a wedge of JB weld on the right side of the skeg to counter the strong tiller torque at speed.

Probably the sliding/steering load is out of adjustment, adjust bolt CW for combo to run straight on a water course when tiller is released, shoud have a bolt around middle swivel bracket for that adjustment. Usually everybody boats with steering load way loose, too much torque is felt on hand while steering along fatiguing your hand needlessly..

Happy Boating
 
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Durango318

Seaman
Joined
Jun 12, 2010
Messages
68
There is a steering friction adjustment and a heading hold lever. They were the first things tried. Using the heading hold transmits too much vibration into the tiller. The friction adjustment on it's own worked, but it had to be ridiculously tight and didn't want to bust the casting. Some tiller friction + the wedge is perfect. Not squirrely and safe.
 

Sinistre1

Petty Officer 1st Class
Joined
May 18, 2010
Messages
298
Durango, what prop did you have on before.? I have the motor and think I should be getting a bit more speed out of it. I have a Saturn 365 and the standard prop and the best I've gotten is 23... I think the motor may be low on the transom though.. lots more splash/ roostertail than I remember with my 15hp Johnson. I was considering changing the prop once I figure out the cause of the spray.
 

Durango318

Seaman
Joined
Jun 12, 2010
Messages
68
Sinistre
I had the stock 9.25X10 3 blade. It's a good pulling and break in prop, but in my opinion it's not a fast prop. I keep it on board in the "go-bag" for rendering help in a tow or in case I found something unseen the hard way. Not working it hard, I've towed a 40' Cruise-A-Home at 5mph with it. Your Saturn is a soft bottom and wider than the norm which will handicap your top speed. If the engine is broke-in (it gets faster) and you haven't hit the rev limiter I'd say your engine is about at it's peak RPM which is where that engine makes power so going for more pitch is not the answer. I'd try the same pitch but with a more efficient Solas aluminum or stainless. The stainless will load up a bit more. With the best prop, trim and height you may gain another 2 or 3 mph in your application. You may need to raise the engine to get the cavitation plate at about even with the bottom of your hull, that is if the clamps don't get to high. If your transom is well built, you can have up to about an inch gap above the transom and bracket. I hate to tell you this but you MUST use the two mounting bolts that came with the engine, not just the two clamp screws in ANY case. If you cross a wake fast and hard, you can torque the engine right off the boat. I almost lost a 15 hp Evenrude that way, I was holding it just the tiller and going in circles!!! God I wish that was on video! That strange roster tail is anomaly comes and goes on mine from time to time as well. It's not weeds. It just seems to be how the water gets started flowing gear case - weird. I've found however it has no effect on speed.
 
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HT32BSX115

Supreme Mariner
Joined
Dec 8, 2005
Messages
10,083
This outboard checks in at only 82 pounds so is very portable.
That is a COOL video...... My Tohatsu 9.8 weighs 81lbs. I have a hard time believing an 18 Tohatsu weighs the same.......

Just saying!
 
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