Tiller trim

[Tellum]

Hi all,I have just PX my t40 for a mercury 420 rib, now I like the open boat approach gives me lots of room for my fishing. I have reserved a 20 HP for this boat , I have seen clip on you tube with same boat getting 25 knots with a 20hp and his boat had a far bit of gear and a folded down canopy. This is more then I got with the t40, My question to you all is ,will the 30 make a big difference and should I get power trim option on tiller? Thanks

[Andy]

And god of @harrison says ............

[harrison]

And god of @harrison says ............

Thank you Father Andy.

Today’s sermon is taken from the Pirates Code.

Thou shall bolt on the biggest, meanest, mother f****r of a motor thy transom will endure.

Go forth and witness the waters part in front of thee.

There endeth today’s lesson.

[Tellum]

always a need for speed , but what about the power trim ? do you guys in the smaller rib find you are using your power trim function much when you are pottering around in your ribs? or is it case of once its set it stay there most the time. i found with the t40 the second hole done the job fine. just curious if i am missing something by not having the power trim option.

[Andy]

Voice of exp, cus I have a T40, is same as you, 2nd hole works best. I also put a half inch wood on the transom to raise the engine, I would have put an inch, but couldn't get away with it.

@harrison taught me, put the most power on you can for the weight. EG the 10 and 15hp weigh the same as the 20hp, so put on the 20, if you dont need it, dont use it.

I would imagine, but no doubt they will come back on this, that for most general duties youll keep the trim the same, for one person, but you have the option to change the trim to the weather conditions. No doubt someone will tell me off if i am wrong, and if the weight is placed in a different way, eg if you put 2 people up front, rather than one person only, then you can mess round with the way the boat handles. More weight at front more trim on the engine, so it planes better. Think I got that right ?

[harrison]

Tellum,

Now for a more useful response hopefully.

As the Ocean Runner 420 is rated up to 40hp then the bigger the motor the better would be my advice.

I’m assuming your running it as an open boat with tiller steer motor. It will go well with the 20hp as fairly light at 113kg but the 30hp will be much more fun. Speed wise perhaps only 5 knots or so faster but will have much more grunt.

Power trim and tilt a very useful addition. The ability to fine tune trim on the fly to suit conditions and tilt for shallow drive is great, and constantly used.

Would I go for power tilt/trim on a 30hp tiller steer? Well yes perhaps, depends on which make of motor. If it needed a battery, as most used to, and assuming your not bothered about increased weight then yes. I’d also probably add electric start as well.

A bit more difficult with the new breed of ‘battery less’ 25/30hp efi motors. Adding power trim/tilt then requires a battery. All depends if your bothered about weight.

Personally I think for a 30hp or more motor, I’d prefer to have power trim and tilt. On a rigid hull the ability to fine tune trim pays off in performance and safety gains.

[harrison]

I would imagine, but no doubt they will come back on this, that for most general duties youll keep the trim the same, for one person, but you have the option to change the trim to the weather conditions. No doubt someone will tell me off if i am wrong, and if the weight is placed in a different way, eg if you put 2 people up front, rather than one person only, then you can mess round with the way the boat handles. More weight at front more trim on the engine, so it planes better. Think I got that right ?

Andy your not that wrong there mate.

Started bashing out a reply but got bored, so lifted this rather long condescending but fairly comprehensive description off tinternet;


USING POWER TRIM
Positive and negative trim – what’s that?
Modern outboard and sterndrive engines have a power trim and tilt system that allows you to adjust the trim, or fore and aft running angle of your boat while underway. Adjusting this trim or hull running angle to suit changing sea, wind and current conditions will improve your boat’s handling, ride and economy.

You might wonder why changing the trim of your boat is even necessary — assuming your boat has been well designed in the first place. However, even the best of planing hulls will benefit from the use of power trim.

The first thing to learn is that changing the drive angle of your outboard or sterndrive leg will change the trim of your boat when it is running at speed.

Trimming or lifting your outboard leg up will trim the bow of your boat up. This is known as positive trim. Trimming your outboard full down or “in” is known as negative trim. This action will encourage the bow of the boat to push down further into the water.

If you think about the angle of the engine drive leg and the thrust of the propeller it is quite logical.

With the engine drive leg trimmed all the way down, the propeller is pushing or thrusting in a diagonally upward direction, and this lifts the stern of the boat up, which in turn drives the bow of the boat down. When you trim the drive leg up, the opposite occurs.

In nutshell, all you need to remember is that trimming the engine up or “out” will lift the bow up. Trim it down or “in” and the bow goes down. In most sea conditions, modern boats perform best with the outboard set so that the boat has a slight bow up running attitude.

That said, when taking off from displacements speeds, many boats will perform better with the engine and the bow trimmed down. This allows the boat to rise quickly onto the plane. Once the boat is up and running, however, the trim of the boat should be adjusted to suit the specific sea conditions.

Leaving the engine and the bow trimmed full down can cause the boat to handle poorly. If the bow is digging or ploughing through the water, the steering will stiffen up, boat speed will drop, fuel consumption will increase, and a lot of spray will be pushed out from the bow of the boat.

Running the boat with the bow full down is also potentially more dangerous than a bow up attitude, given that when running downwind or before the sea, it can encourage a broaching situation.

Having made these comments, trimming the bow full down can make your boat ride more comfortably through the water, particularly when running upwind or into the sea. Trimming the bow down allows the sharply angled forefoot of the bow to cut, like a knife, through the chop, improving ride comfort.

Conversely, trimming the bow up is important when running downwind or in a following sea to keep from broaching. In normal running conditions, however, it can be inefficient to trim the boat up too high. The boat will have trouble getting onto the plane, it may ride harder, be inclined to leap off waves, and it could also develop a porpoising or bouncing action, even in calm water.

[harrison]

Tellum,

Chapter three. More thoughts, sorry.

Portable outboards, up to and including 20hp, weight is paramount. On and off transom, so lightest option... no power tilt/trim, no electric start, no battery. Simples.

Medium outboards 25hp and up, not portable, live on transom, boat lives on trailer. No benefit not having electric start, power tilt/trim, battery. Simples.

There’s your answer.

PS: Not much response on t’other channel.

[Tellum]

other channel is quiet i thought being a rib site i would of got me a lot more responses. thanks for that harrison, the wording you used, very useful addition and constantly used is basically what i needed to hear before i part with close to 2000 pound extra for a new 30 hp with multi functional tiller compared to the nearly new standard electric start 20 hp.

[Tellum]

also as for the weight issue, the reason i sold the t40 was because it lived on the trailer behind my shed ,so small open rib seemed the way to go. the 420 with a 30 will suit me for a long time i believe. may be when the last sibling is less dependent on my time and money i might go bigger , got the room for a 5m but not the finances.