Not getting a desired speed

[Faztbullet]

Will remaind you all that all Tohatsu motors have way taller lower leg plates compared to other brands. So cut the cast on stone crap that must be even with rear middle hull...​

This set up only apples to Tohatsu motors not other brands. No matter the height that boat/motor will not run near 40MPH

As I can tell, not assume, none of you guys have in use or know well these 2 strokes Tohatsu motors​

Bovine Scat ...I work on quite a few when I can get parts as no dealers around Tennessee and was also a Nissan dealer (same motor) so yes I know these motors.

 

[DeepCMark58A]

Couple of things a different prop will not create more horsepower, the motor is not coming up to full RPM because it is over loaded by the weight being pushed. The motor on the boat will never push the boat any faster than it does now.

 

[ahicks]

Couple of things a different prop will not create more horsepower, the motor is not coming up to full RPM because it is over loaded by the weight being pushed. The motor on the boat will never push the boat any faster than it does now.

Suggest you reread post# 18, the part about hitting a log. Depending on just how damaged that prop is, I would suggest there's a VERY good chance it will go faster than it does now.

 

[DeepCMark58A]

I am sure the OP will bask in the 2 mph increase in speed.

 

[Sea Rider]

Thanks OP for finally showing up..

Forgot to ask if this is 40 HP tiller or remote model ? Revving at idle means nothing, what counts is the motor revving fully at load while pushing a boat.

If it were my combo would start troubleshhoting the prop condition. As you don't know if the current prop performed well and if repairing it at a prop shop costs much less than buying same new one go for it. You could have a spun prop already which the prop shop will tell for sure. If the total repair cost exceeds a new one, then order a new OEM with one less pitch from current one, will achieve higher wot rpm.

After installing an induction tach and water testing any of both prop scenarios on a wot run will know if the motor is 100% healthy and the max rpm achieved and was only a prop issue. If you want to count with the full 40 HP written on the cowl need to prop ithe motor right as loaded for motor to run towards its max 5800 wot rpm range.

If that boat is rated for a 75 HP max motor, don't see why a healthy 40 HP well height seated and max propped to run to its full 40 HP won't perform excellent with half or much less number of passengers stated for.

Hey FB, your great post has contibuted -00 trying to solve the OP's post, why is it that you always love justifying yourself at with what i post, usually pickin on them, bashing, discrediting which you love doing. BTW, Tohatsu has 98 years manufacturing excellent motors, being a Tohatsu eminence should know well the Jurassic first ones for sure...

Happy Boating.

 

[jimmbo]

Since the current prop is banged up due to a Strike, there will be an return to previous performance levels. However, the only way a 17 ft boat with a 40 Hp will go above 27 mph, is on a trailer, or if it is a Racing Hull

 

[hunter24]

So I took the prop off, and the only words/numbers I could make out was "TOHATSU." And how would I install a induction tachometer? And I apologize again, I'm newer to the boat stuff. I got some pics of the boat, prop, and motor data tag

Pics

https://ibb.co/Dkwsxw2

https://ibb.co/7p0tV3n

https://ibb.co/pz3h84z

https://ibb.co/d4MPC7G

 

[jimmbo]

Induction Tachs have a clamp that fits around a Spark Plug Wire

That Negative Cup(bend) on the blade(s) will certainly affect performance

 

[hunter24]

Induction Tachs have a clamp that fits around a Spark Plug Wire

That Negative Cup(bend) on the blade(s) will certainly affect performance

That happened from last time I took it out. Before it got bent, that's when I did the speed test

 

[jimmbo]

You don't know what rpms you were getting prior to the Impact, and running a bent prop is no way to establish a Baseline, you need to start with an undamaged prop, then go from there

Since you bought it only a couple of weeks ago, have you done a Compression test on it? Doe all Cylinder have spark and are carrying their share of the load?

 

[hunter24]

You don't know what rpms you were getting prior to the Impact, and running a bent prop is no way to establish a Baseline, you need to start with an undamaged prop, then go from there

Since you bought it only a couple of weeks ago, have you done a Compression test on it? Doe all Cylinder have spark and are carrying their share of the load?

I checked for spark and put new plugs in it before I first used it. I havent had a chance to do a compression test yet, I'll try to get the stuff to do it tomorrow

 

[Faztbullet]

why is it that you always love justifying yourself at with what i post, usually pickin on them, bashing, discrediting which you love doing.​

Just trying to correct the misinformation you love to post...You disagree with other OEM manuals and MFG posted set-ups as Tohatsu way is only way to set em up...which is not correct..

 

[Elkins45]

This is the tach I bought to verify my engine RPM: https://smile.amazon.com/gp/product/B07LF97ZBY/ref=ppx_yo_dt_b_asin_title_o01_s01?ie=UTF8&psc=1

 

[GA_Boater]

This is the tach I bought to verify my engine RPM: https://smile.amazon.com/gp/product/B07LF97ZBY/ref=ppx_yo_dt_b_asin_title_o01_s01?ie=UTF8&psc=1

Try another source - Currently unavailable and We don't know when or if this item will be back in stock.

 

[Sea Rider]

Elkin,

This Hardline hour/tach will work well, https://www.hardlineproducts.com/pro...ourtach-meter/
Check if IBoats or Amazon stocks them. Set it for 2 sparks per revolution. Have installed many on different Tohatsu motors, next to the tiller's grip as seen, install same if your motor is a tiller model and at front cowl if being a remote one.



Now that you have removed the prop, take it to a prop shop and have it tested if having already a spun hub or not, if found OK have them re worked to a new condition, test it and report which max wot rpm was dialed if you can go boating ?

Hey FB, hold your throttle down, you are the one that swears by Neptune that all motor installations must be done with AV plate set even with middle rear hull. Would like to know who was the first moron who thought to say that tech fallacy and everyone following it blindly. Not a single Other Brand Owner's Manual states so, have taken the time to read them all and have said so many moons back.

Gee, being a Tohatsu eminence should know that both plates compared to are much taller than Mercs ones which are way shorter. You're the one that never reads, investigate, tests, like to assume, think things, Understand that's proper of the ones aging badly and nothing can be done about it.

You won't be able to contradict nor bash what I currently post as was dialed on pure experimentation through the years. I'm the only one posting pics, videos, graphics to school others and don't lose precios boating time going off course. What's your contribution to the forum asside from the usual scratched record monosyllables written answers...

To end this stupid discussion with you will say that you can sit any Tohatsu motor at any other height from the spot height I like to state, but won't achieve the excellent water results as seen on the posted video as the prop will aerate, much worse if the motor runs towards the max rpm range. Let the OP test for himself what posted when his motor is running strong again. If you don't want free on-line confrontations with me, just say what you have to say and don't quote my posts and will live iboth in peace, Amen!!

Happy Boating

 

[JimS123]

Except for the biggies, many of the Mercury outboards are actually made by Tohatsu and rebranded with Mercury black paint. Other than decals and color, the AV plates are the same.

The guy that set up the Boston Whaler in post #17 was obviously a newby and he didn't experiment all the way. Whalers come from the factory optimized for performance, and the engines are usually set with the AV plate level with the bottom. In my case, its up 3 notches.

My SeaRay was also set up beyond my expectations. The AV plate is an inch above the bottom. I still am amazed at the speed and fuel usage.

 

[hunter24]

This is the tach I bought to verify my engine RPM: https://smile.amazon.com/gp/product/B07LF97ZBY/ref=ppx_yo_dt_b_asin_title_o01_s01?ie=UTF8&psc=1

Just ordered that, should be here by may 9th. And I wont be able to take it to a prop shop or out anywhere because New York just shut down all marinas and boat launches

 

[Sea Rider]

The guy that set up the Boston Whaler in post #17 was obviously a newby and he didn't experiment all the way. Whalers come from the factory optimized for performance, and the engines are usually set with the AV plate level with the bottom. In my case, its up 3 notches.

Water performnce has to do more with how efficient the hulls is along the less water drag the hull achieves than the boat's transom height. The less hull drag coeficient the better will run with whatever is being powered.

So by watching a simple video you already drew your own technical conclusions. The story of this water test is as follows. It was indeed a newbie, his motor was experiencing middle back water splashes due to the lower leg was sitting too low while the motor sat flat even on transom,



water flow at speed was banging over the upper small plate, told him to sit motor at 90 deg and to raise it with wooden shims accordingly till the back splash was totally canceled.

He was so content to have solved his motor/combo installation that agreed to post that YouTube video, I use it as a visual reference to go for, UK, Australia and foreign boaters have set their Tohatsu motors as shown and now boating happily after. The big issue with you guys is that NO one visually checks what's going on at back transom to top match their engines to their boats. Sorry guys but Tohatsu it's my territory to whoever bothers...

​​​​​​​That's why each combo and motor brand needs to count with a Unique Installation. What's the point comparing a BW with a SR if being powered with different HP brand motor. Comparisons does nothing to solve nautical problems, rather confuses the OP's requesting technical assistance.

To the OP, hope that the ordered tach has a variable spark firing sequence setting, if doesn't count with one, the tach will render useless, that 40 produces 2 spark per revolution. If the tach only counts with one spark setting will read double and only to max 9,999 rpm and that motor revs at 5800...

Happy Boting

 

[JimS123]

The BW / SR comparison was merely to illustrate that when boat companies design for performance the AV plate is never positioned below the bottom of the boat.

For the little boats I've owned that had clamp on brackets, frankly I never bothered with performance curves. Its a 10 HP fishing boat that goes 18 MPH and uses 3 gallons of gas all day long. What's the point?

Using shims is a possibility, I guess, but all my bigger motors have had holes in the bracket, so merely adjusting bolts was all that was needed to giterdone.

Tohatsu and Mercury are synonymous in many cases.

The picture of the Tohatsu and back spray looks weird. Never saw anything like it. Must be an odd hull.

 

[Sea Rider]

Some issues :

-Why does the AV plate should never be positioned below the boat's bottom or even with it when NO motor brand states so which Confirms that NO one reads the Owner's Manuals tech specs for their respective motor brand.

-At the time you and I starter going boating, you with a 10 HP motor and myself with a 10 HP Evinrude one, there wer no online forums to ask or seek information and very few props to play with, will assure that now knowing all you know about, boating, counting with tachs and different props pitches to play with both combos if still were owning them will benefit way more achieving a much better water performance compared to the good old days.

-The huge splash seen on my last post was due to that specific boat's transom height was not matching a Tohatsu 18 HP motor's lower leg. A transom height modification cured the problem. Tohatsu motors have tad larger lower legs compared to same Yam HP one no matter if being S or L ones. Install 3 different brand manual trim motors on same transom height and all 3 will perform differently due to a design issue..

-Clamp screw motors are way much precise to sit properly on transom as you can shim up or shave down any transom height by the milimeter whereas a bolt on motor won't as the distance from each hole is fixed and way more than one milimeter to properly play with.

Seems we all will need to stay home for some more time till the OP's combo sees water again and report his findings...

No Happy Boating