Increasing Performance 30Hp Suzuki

[Tinn]

Hey people

I have a brand new 30hp suzuki engine on my 4.2m tinny and are looking of ways to get more go out of it with out changing the engine to a 40hp. I have heard of guys swaping the prop. Is there anything else you can do to get a bit more go out of the engine? If not what is the best prop to get for this engine?

Thanks

[Noelm]

just swapping the prop will not increase HP, but, it may enable the motor to run to it's full RPM, you need access to some sort of tacho to see if your engine is acheiving top RPMs as too large a prop will cause the engine to be "loaded" all the time and will surely cause early failure, there has been hundreds of articles written about changing a 30 to a 40 and so on as they may share the same enging block assembly, but there is usually far too many differences to make it a viable option.

[Tinn]

Lets say I am reaching the right RPM (don't know much check that) is there anything else you can do to get a bit more push?

[Noelm]

not a lot, sorry, except a bigger HP motor,or, dump unwanted load from boat (unlikely) you could fit the next size prop down and give you a bit more power, but you will loose in top end speed, most important is the motor reaches max RPM reasonable easy usually 5 to 6,000 but check manual or ask dealer for help if it is new as you say, a good dealer will help you with setup or, at least should if they want repeat business

[Noelm]

dealer help with setup may include checking motor height as well as RPM by the way.

[Tinn]

I have raised the engine because the bloody dealer mounted it to low
(i had rooster tail out the back of the boat) that improved things alot still am getting spray thou. Got it checked by a boat place and they said the motor is correct I think it may have to go up until the spray stops.
?
Will the boat improve if I prop it and stop it from spraying ?

[Az]

i really would have a thought a 30 on a boat that size would be pretty quick, is it a 2stroke or 4stroke?

going flat tack in my mates 3.85 with a 25 is bloody scary

[Noelm]

can it be raised any more?? next time you are out on smooth water, look over the back when on the plane and see if the cavitation plate is just skimming along the surface, if it is below and you can raise it up "another notch" then do so

[Tinn]

It can be raised only another inch more then if you go any higher the clamps will have no where to clamp to the transom.

Okay I will check the cavitation plate when I go out next.

AZ: Its a 2 Stoke I wouldn't say it is scary it goes quick but not scary

[Tinn]

One thing I have a query on if anyone could answer is when two people are in the boat the motor sprays some water if i have 4 people in the boat there is no spray at all from the motor, can someone explain to me why that is?

[Dodgy_Back]

Hi Mate

I have a little 30 hp on a 4.25 and I too was a little frustrated with lack of speed.

A couple of things that I did, although it may sound pretty obvious to most was,

Take off the foils on the leg, takes a fraction longer to get up on the plane but I gained a little speed.

Trimmed the motor right up, this helped a lot but not too good on tight corners.
And lastly took it to a mechanic to make sure I get all the throttle available .

It may sound pretty basic but doing all that I was able to get a bit more speed
Mick

[Tinn]

Thanks for your input mate. i don't have a foil so that is not a problem. I might try trimming up the motor and see how that goes

thanks again

[saurian]

Tinn , sounds like 4 people helped your trim ( forward /aft balance)
Maybe play around with trim settings next trip but sounds like motor maybe not setup to the right height.

[Tinn]

Here are some pics of the engine height in normal trim position

[Tinn]

Another in normal trim position

[Tinn]

A photo taken from the other side of engine

[Tinn]

Picture of engine trimmed fully out

[Tinn]

Another pic of motor fully trimmed out

[Tinn]

Picture of engine clamps

[Tinn]

another of the engine clamps

[Tinn]

Photo of the transom

[Tinn]

Now righty o all you boating gurus what do you have to say about the engine height on my boat? I think it has to go up

But the clamps are nearly at the top of the transom anyone got any ideas to fix spraying problem?

[Tinn]

Comeon people there has to be someone that can help me fix the problem.

You would think a boat yard could help but they told me it is all good. So you are the only guys that can help me

[billfisher]

What speed are you getting? Maybe you are expecting too much and don't really have a problem. I get 24 knot (by GPS) top speed with a Suzuki 30 hp on my 4.1 polycraft (a heavy boat). This is with just myself, but a passenger doesn't seem to slow it down any.
PS I think this is fast enough for a tiller boat.

[spudie]

hi tinn , lookin at those pics. its not right. you need more hight & you need to trim yr motor out alot more.you need to get your cav plate in line with yr keel. just under is best ;)

[spudie]

where are you tinn? you need to bild up that transom. did you buy the boat& motor as a package??

[Tinn]

Billfisher: Not sure what speed haven't measured it yet will have to buy a speedo. Ever since I raised the motor the boat seems to go alot faster but it still is spraying water which must be slowing it down. It still feels a liitle slugish. Like it just needs a bit more push

Spudie: How much higher and how much more trim do you think it needs?

[Tinn]

Yeah I bought the boat as a package deal. Not happy with the dealer for setting it up wrong

[spudie]

what it takes to get the cav plate inline with the keel. trim motor tell the top of the cowel is level when going at top speed. then trim it up alittle bit over level. if you go to far itwill handle like a dog.

[Tinn]

Mate what is the cowel also you said to get the cav plate level with the keel is this when the leg is in vertical postition?

[Blackened]

G'day
The cowel is the cover for the engine. The bit on top you take off to get at the powerhead. I think what spudie is getting at is the top of the engine(cowel) should be parralel with the water in which you're traveling at planing speed. This will have the engine at the right angle with regards to trim positions. In theory the anti cavitation plate should be level with the water surface, sitting just under it and the trim angle will adjust the angle of the boat in the water, negative trim willb ring the bow down and increae friction with more hull in the water and positive trim will bring bow up, less friction and less hull in the water. You aim is to find a happy meduim. The anti cavitation plate should be level with the bottom of your keel (there abouts) as anything but will cause excess drag. You will need to raise this engine further still. Does it have the right length shaft or should you really have a shorter shaft engine on this boat?
Dave

[spudie]

thats it ;D

[rojac]

The set up diagram in the motor manual recomends that the cav plate is 25mm under the bottom of the boat.

If the boat is designed for a ls motor and all(?) the ls are 508mm, then it may be that the leg is too long or the transom is too short. Maybe one of the components are the incorrect length otherwise it doesn't seem to make much sense.

Surely the manufacturer wouldn't design a hull that cant be set up.

[spudie]

the problem is that most of the dealers are just sales people nothin else.

[Seahorse]

i got 30hp merc on my 4.2m. i moved it out to 3rd hole from transom. made steering a lot lighter, but i notice water coming up from behind transom like a bubbling spa bath with the jets turned up, but nothing in boat. i got my hand held gps out that i dont yet know how to use and the speed said 32k on a flat day. i thought that would be klms? 32knots sound to fast. i had foil on but lost top end speed. top of cowell is dead level when travelling.

cheers
greg

[robersl]

i also have a 30 hp suzuki i find it gets along ok but in saying that the leg does sit a lot lower in the water than my yamaha 40 used to even when the motor is tilted i find at the ramps i have to have the back of the boat out further before i can drop the motor to tilt and start it the motor has been lifted by the dealer onto a plastic block on the transom and will not be able to come uo much more either the trouble i had was the boat pulling to 1 side so i had to adjust the anode above the prop

shane

[Blackened]

g'day
Greg, at a rough guess i'd seriously imagine you'd be gdoing 32kph, not knotts. Reasoning is i have a 12' tinny, 9.9 merc and flat strap it does 35kph (about 20kts). The power to weight ratio would be somewat similar i'd imagine,
Dave

[Roughasguts]

Hi Tinn, Think you got two choices here.

As said before raise transom height all you need is a rectangular section of aluminium same thickness as the top of your transom, looks like you may need around 70mm gain in height.

Anyway then some alloy plate comming down both side of your transom welded to that rectangular section and put some long through bolts through it all to clamp it nice and tight to your existing transom.

And of course fill the old bolt holes.

That be the best option.

Then theres those foils that will help lift the arse of the boat up and out of the water and get the bow down that will increace your speed.

But really that be the band aid solution and I'm not a beleiver in foils to any great extent. They will change the handling of your boat and can give you a bit of a fright until your used to it. But still there a cheap fix and work well if you have a lot of weight in the back.

[7dan7]

I had a 3.75 allycraft + put a 15hp yammie behind it + had the spray problem the transom needed another 60mm. i got piece welded in + fixed problem. motor is definitely to low if you are getting spray.

cheers dan

[Tinn]

Okay guys looks like I will have to build up the transom. Anyone know of a good place to get the welding done?

[spudie]

iwhere are you

[Tinn]

My boat is located at eight mile plains brisbane. Must fix this spraying problem. I think it will probably go alot faster if it is setup right

[billfisher]

I don't think foils will help top speed. At full throttle they just create drag and you will lose a knot or two. They are good for getting on the plane quicker and maintaning plane at low speed.

[Tinn]

I won't be fitting a foil. They slow down your top speed. Will be lifting the motor tho so I can stop the spraying and try to get the top revs out of the engine. Maybe even getting a different prop will see what revs I get once I lift the motor up

[ahoj]

-----If your motor runs at full bore and you take the eccelerator slowly down without reducing speed of your boat to say 70%-- then your motor is overloaded and can not push your rig to full speed-- reducing your impeller's pitch down will make your motor reach top revs and the boat speed will be relatively the same as before( perhaps marginally faster)
If you increase the pitch you will overload your motor and perhaps only run at 3000 rpmand you will delete your motor soon

Load and load distribution can help your boat to get up Your boat should do around 45Km/h with 30 Hp. There is a posibility that your max rev screw needs adjustment. check your filters-- air and Fuel and timing compression test will help you to discover that you may have a problen somwhere else...

Ahoj

[Tinn]

Thanks for your help ahoj but I think the problem is the height of the engine. As it is draging in the water and spraying water up in the air. It use to be really bad before I lifted it. Since I have lifted it the performance has increased dramatically and spray has decreased alot but there is still a fair bit of spray so I think the motor has to go higher.

[ahoj]

From examining the pictures i feel your motor needs to go up 2 more inches --50mm Pitty you have no more transom left-- use screws only- your Trim is also too close go 2-3 rd slot or more away from transom.. see how you go...
Is your motor Long shaft?

Ahoj

[ahoj]

Cav plate should be level with the boat floor then cav plate 25 mm below the transom that is the usual distance and efficency then small trim adjustment will give you the speed and surfing------ do not try to bury your bow into water in order to get the bum up it wount' work and its dangerous

You will sort out your problem shortly i am sure Cheers Ahoj

[saurian]

Tinn, i think iam 12 hrs late on this one , motor needs to come up ..
I noticed bolts through transom ???
Screw the clamps , i have 40 hp suzuki and the same clamp position would be 40 mm higher than transom. Ditch the clamps and bolt her to height , maybe no need for welding job ??? Note question marks , iam only looking at your pictures. best luck.

[saurian]

Tinn, measure height of transom to bottom of boat, then measure from top of cav plate to screw in clamps , and i will check mine .
Mine is longshaft.

[Dory4.1]

Mate, talk to the mechanic at your local dealer. I'm not familar with your particular model , but I know my old Evinrude can be modified by carbie changes etc from a 20hp to 30hp+. I've never gone down this path because it would be cheaper for me to buy another outboard!

[saurian]

Tinn , just measured it and looked at your photos again , my cav plate is at the same height as your first lip on leg above the cowl plate ...!!!
Looks like you bought a xl long shaft ...
My transom from top to bottom of boat ( NOT KEEL) is 490 mm.
My leg from transom plate to holes where screw brackets would be is
approx 550mm.
My screw brackets if installed would pass nearly through the top edge of the transom. Looks like a lift is needed , try bolting it up if you can as paint will look crap after weld job.

[MyEscape]

How fast is not fast enough?

I have a 4.15m Seajay pro with a full floor (it's not that light), canopy (to create some wind drag) and with 2 people it fairly flies. In fact most times I would only run at no more than 1/2 throttle.

Fair enough I'm not sure of the exact speed, but it's quick!

Steve

[MyEscape]

Oops, it's a 30hp Yamaha 2 stroke on it.

Steve

I new that there was something missing from the last post!

[ahoj]

30hp Yamy and 30 suzi are both good motors I have asked Tim if it was a long shaft I had a suspicion it may have been( no answer) if it is then you can build your transom by at least 150 mm.. (My meassure is an estimate only)).When you bought your motor you didn't match motor to transom.... nothing lost-- good experience.. As Saurian sugested go with bolts and even if you were to extent the transom you can then use your clamps.... In your case the clamps are quite useless.. do your test first and then setup your transom hight..

Use a spirit level for measuring your boat bottom and cav plate on your motor.. both should be at same level and then Motor 25 mm below..

Not easy to manouver your heavy motor to lift your motor to where you want it exactly use your front jockey wheel that will help but need a mate to help you

Ahoj

[MyEscape]

Ahoj,

I'll post a photo later this morning with my set up. 30hp yammay on a 4.15m Seajay. n the position that it flies.

Steve

[Spaniard_King]

Hey people

I have a brand new 30hp suzuki engine on my 4.2m tinny and are looking of ways to get more go out of it with out changing the engine to a 40hp. I have heard of guys swaping the prop. Is there anything else you can do to get a bit more go out of the engine? If not what is the best prop to get for this engine?

Thanks

You look to have the wrong size leg for this boat, take it back to the dealer in question and have him fix the problem. If you have no joy with him take it up with the boat and engine qld managers. If you did not make the decisions in what engine to put on this boat then it's not your problem it's the dealers!

Mention the small claims court 1 on 1 to the dealer if he isn't interested ;) (be prepared to follow this thru)

Garry

[saurian]

Tinn, i think spaniard might be on the money here . Everytime i look at your photos , it looks like short shaft boat with a long shaft motor.
Maybe take boat to another dealer first to check sizes , then go to
original dealer and follow spaniards words of wisdom.

[ahoj]

There is nothing wrong with long shafts in fact they keep dryer... Did you buy the motor from a dealer? or other source.. I am sure if its the dealer he will not change the motor but may refund you the extra money you paid or if not ask him to help you to set it up. One way or the other talk to your dealer.. and compromise.. by the way what did you pay for your suzzi?

Courts are ugly places and no one wins...

You must be disapointed for not being able to buy and set it up and go like a wind.. but don't be your pleasure will come soon and you will be pleased once again...

Ahoj

[Spaniard_King]

ahoj,

Why should he compromise ??? #::)

He has purchased an engine that is incorrect for his boat, If the dealer chose the engine then the dealer is at fault. Shouldn't Tinn get the correct engine for his boat? I am sure he worked hard for his $$$ like most of us do.

"Courts are ugly places and no one wins..."


Small claims courts do not cost much It's only when lawyers get involved. If he took the dealer to small claims court 1 on 1 the dealer cannot bring a lawyer so he gets to say his piece and if he has paperwork and pictures to back up his story what do you think the outcome would be ::) If the dealer does not take it seriously Magistrates luv to stitch people up for not turning up ;)

Small claims are for just that, not sure of the details but I think free legal advise is available for disputes like this (if it gets to that) from the small claims court as well.

I will see if I can dig up the info

Garry

[billfisher]

I just compared the photos to the height on my Polycraft. I have longshaft 30 hp and the cav plate is just level with the bottom of the hull. I get good performance with this set up.

Iwould be welding up square section of alloy to your transom to raise the motor to this height. Looks like you will only need a couple more inches. As ahoj mentioned it wont hurt to have the powerhead well clear of the water.

Having the engine too low doesn't do it any good over the long term as it is put under extra load.

[ahoj]

What i am sugesting is -- disputes are not the answer --solutions are.. Tim may have inedvertantly agreed to buy long shaft or was not sure what he was getting and the consequences------ which came first the boat or the motor??
Ahoj

[rojac]

Tinn

What type of boat do you have??

cheers

rojac

[Tinn]

It is a Clark Cutter 4.2m. Looks like I will be welding a square piece of aluminium on the top of the transom to build up the transom then bolt it all in place.

[Tinn]

Guys the boat was bought as a package deal from a dealer but he is too far from me to take back. He told me that is the right motor for that boat as specified by the boat manufacturer. He recomended to lift it as high as possible so I took it to another well known boat yard in brisbane and they said they would lift it to the correct height. but it still sprays water so I will build the transom up and fix it myself.

[ahoj]

Bravo --Bravo --(silently clapping hands)--Materials 20$ welding 50$ and paint 10$ helper to set it up 2x 6 pack 20$ and satisfaction beyond cost... good thinking 99......

see you on the water at weekend #going past me like a ROCKET #WHO WAS THAT that was speedy Tinn #lol

Cheers Ahoj

[Noelm]

HI
Just got back from a break, and your motor was way too low, glad you got it fixed, not too sure what the dealer was thinking there!

[Jeremy]

It is a Clark Cutter 4.2m. Looks like I will be welding a square piece of aluminium on the top of the transom to build up the transom then bolt it all in place.

I may be wrong, but I believe that you do not need the clamps if you have the 4 bolts thru the transom. No welding required, just lift the motor on the bolt holes available.

But honestly, this is the dealers problem, not yours. Don't let them get away with it or the same will happen to the next person.

Who was the dealer?

Jeremy

[Tinn]

I would prefer not to mention the dealers name.

You are now confusing me what is the best way to fix the problem. 1. Just put four bolts in the transom or 2. build up the transom

Any opinions what I should do?

[Stevo25]

If it were me with the same problem i would be going back to the dealer.

Building up the transom might solve your problem, but when you want to sell the boat
any buyer that knows somthing about boats and motors will know it looks out of place so
also think of resale value.

Going back to the dealer, he either has to replace the leg for the correct one or replace the outboard,
this is where you may be able to strike a deal and get a 40hp at the same time.

Good luck with it.

[Noelm]

OH sorry I must have misread, I though you HAD fixed the problem, and I am with the other guys, it is worth a trip back to the dealer so as you do not "fix" the boat and void the warranty or something! at least call them and explain that you have the motor at the very top of the transom and the cav plate is still a few inches below the bottom.

[ahoj]

Why all the confussion???? Tinn is ready to do it all correctly and cheaply and go fishing Time for action now no arguments please... #If Tinn #increases the hight of transom he will have a dryer boat #More then most of you with short shaft#------Go #Go #Tinn

Ahoj

[Spaniard_King]

Ahoj,

no one is arguing. It's a discussion about an engine that does not perform correctly.

It's great nto get it fixed but be aware that the strength of the built up transom should take into account the design of the boat. There is a little bit more to it than just raising the transom. I would think it will need to be reinforced somewhat when the engine is higher it will place more force onto the transom... put simply it will have a greater mechanical advantage than before.

Also you may take away the look of the boat and likely have more difficulty in selling the boat as it will not be standard and if not done professionally may look out of place.

cheers

Garry

[saurian]

Tinn , measure your transom.Post it.
measure outboard leg cav plate to centre of screw nuts then post it.
Then everyone may be able to give you a realistic solution.
I would not just go and weld it , the bolts sound like a better fix in my book.
I have a clark , interesting to see if transom is the same..???

[Tinn]

Okay guys I am going to measure the transom and leg and let you guys know.

Before we go any further I took the boat out yesterday for a drive with the motor trimmed out one hole there was no spray from the motor. I looked for the cav plate but you can not see it it is under the water line. I will also measure exactly how far the cav plate is under the keel of the boat but just guessing it looks about 25mm which is correct according to you gurus.

I will be back with some measurements tomorrow.

[Tinn]

Okay guys I measured the transom and it is 480mm high and measured the cav plate to the centre of the screw clamps 520mm high. My cav plate when level is sitting 35mm under the keel at the present moment.

Now I ask what is the solution to my problem?

[blaze]

2 choices

take it back to the dealer and get the right motor fitted
build up and strenthen your transom
cheers
blaze

[robersl]

tinn
as per pm hope this helps you

[robersl]

and

[robersl]

and

[robersl]

and

[saurian]

Tinn , your transom is only 10 mm longer than mine, cav plate should be about level with bottom of boat not keel , sounds like you need to come up about 35 mm . Would that then put your cav plate in line with bottom of boat ??If it does work out will you have any screw purchase on transom available??.
The deal you got in my books is not fair, but if you would rather sort it yourself , you might have to see if bolts between outboard and transom
can be moved up and motor put higher up. Another dealer closer if told of the last dealing , may put your faith back in the marine profession .
I think a small amount of money for welding up old bolt holes and new bolts etc..
Will sort the problem ,

[Tinn]

Thanks for the photos robersl that was very kind of you.

Saurian: If I come up that high I beleive I won't have any screw purchase on transom left.

What should I do people?

I am very confused in what to do.

[ahoj]

here here sarian

[Argle]

Mate I would be taking it back to the dealer who sold it to you as Garry(Spaniard King) suggested, and get him to fix it either by changing leg length or modifying the transom to suit. I would not be modifying the transom as this could lead to insurance/resale/cosmetic pain further down the track. Its not up to you to fix a dealers mistake. When I bought my boat the dealer set the trailer up incorrectly, it was taken back and fixed at no cost to me and now is as it should be. In the end its up to you but I know what I would be doing if it were me.

Cheers and Beers
Scott

[Tinn]

I spoke to dealer this morning he recomended to me to get a piece welded onto the transom. I am very unhappy with the dealer never to use them again or speak to them again. He told me that the cav plate should be 15mm under the keel which means 25mm under the boat curently it is 45mm under the boat meaning a lift of 20mm is needed. So before I first lifted the engine the cav plate would have been 60mm under the boat and he tells me it should have been 25mm what the f were they thinking when they put the engine on can't understand they know where it should have been mounted. I will be lifting it 25mm by placing a 45mm piece of aluminium on the transom then bolting the engine in place. I will then see where the clamp screws end up take it for a test run then get the aluminium welded. Screw the dealer and other yards do it yourself and you will get the job done.

not happy :( :(

[Tinn]

Saurian: I forgot to tell you that I already got another well known dealer to lift the engine should have just done it myself. They assured me that the engine should be where it presently is. Every one that has seen the engine at boat ramps freinds ausfishers say it must be lifted so musch for good service from a dealer that we all know. 2 Dealers both didn't fix the problem

[Jeremy]

Tinn,

the best height for your motor is always worked out by trial and error. Guesses and recommendations only go so far. As you say, try it out first and if it works good, make it more permanent.

BTW, I believe that it should be as high as possible without excess cavitation/ventilation on turns. A small amount is acceptable.

Let us all know how it turns out.

Jeremy