Steering question on 1974 20ft CC SF
 

Just finished two test runs on my newly repowered 74' CC (115 H.P. E-TEC). All went well, engine ran smooth and quiet as cats paws.. and the scuppers are draining well (down) and keeping the water where it is supposed to be.
I noticed that the steering was free and easy up to about 15 kts and from there became progressively harder as I moved up to 25+ kts.
My E-TEC dealer, who is familiar with Seacraft suggested that I trim the engine forward, at speed, until just about when the prop breaks free, then back it down slighly. He states that this will give me easy steering and improve my overall numbers by about 10%. Says that having the engine tucked down tight to the transom is what causes the issue.

I would appreciate any comments members might have on this situation.

Thanks in advance.

Please post performance numbers when you get a chance.

I have a 1973 20sf with a 06 yamaha 115 on it. I find that after planeing off ill trim up and gain some speed but i lose steering. I have much better steering with the motor trimmed down.

Cable steering? If so hydraulics will solve all your problems

I have a similar problem with a Yamaha F100 and Teleflex "No Feed Back" cable steering. I think hydraulic steering would be great, but trimming the motor mostly solves the issue. I go faster trimmed like this, too. I have the anti ventilation plate 1 to 1.5 inches above the keel.

There are different steering ratios available too, so you can get more mechanical advantage at the wheel. I didn't try it, but it is probably $150 to try something different.

Thanks!
 

Thanks for the input. Most appreciated.. will report back after the weekend

Steering problem
 

Even my money problems if I buy a hydro system?

Well, almost all your problems... haha

Steering is a trade off. I've had hydraulic and cable and cable is not so bad. I put a NFB 4.2 on my 20' with a 115hp and am pretty happy. What I like about hydraulic is it is easy to steer. What I like about the cable is it stays where it is when I let go of the wheel. We used to actually bungee the Seastar wheel to the t-top on my old boat when all day tuna trolling which was a real pain. I did have autopilot but it was a bad system and quit on me so back to bungee, lol. What usually makes cable steering over tight is tight radius bends. I'm having no trouble WOT trimmed in or out with steering. If your having trouble at speed, maybe the anode tab needs to be adjusted?

Steering
 

Thanks...boat tracks very straight....so it may be the tight radius...however at low speeds..it is free and easy.

I will be testing the trim option tomorrow and report back

If you aren't using the bow to break waves in a headsea, the motor should be trimmed up. Look at the wake and trim up until the bubble or v is gone. Ideally the water will look like its coming off the bottom of the boat perfectly. Getting as much of the length of the boat out of the water at cruise is key. Saves gas, easier on motor, faster. I don't know if this is common knowledge or not as I see it waaaaay too often.

Numbers
 

Only able to get max 5000 rpm at WOT.
Max speed is 28 its.

Prop is a 12 7/8 X 15 Viper.

I would think you could get 30kts, or 29.5? Raising the motor 1 hole was good for 300-400 RPM for me. (6000 redline, 1:2.31 gearcase ratio) It slightly helped steering effort, too. I can pull about 28.5 kts with a F100 on a light 20' Master Angler. 13" x 15" pitch 4 blade aluminum stern lifting prop to heave a 4 stroke + 4 stroke kicker up out of the water. Rest of the boat is light- 20 gallon tank, no T-top, no live well. Empty cooler, aluminum anchor. Batteries under console.

Prop is a SOLAS Amita 4

My old 1975 115, that was really only about 100 hp at the prop, used to spin an OMC 13 3/4 x 15P 3B SST prop up to 5500 rpm. Your motor is about 120-125 hp at the prop, so I suspect motor is mounted too low if you can't spin that small prop any faster than that. You should be able to clearly see the top of the AV plate above the water when you're up on plane and motor is fully trimmed out to a point just before it starts to cavitate.

All motors are harder to steer when you trim them in towards the transom. You can adjust the trim tab aft of the prop to offset that prop torque effect.

motor is mounted too low, as Denny said creating both problems, thats why the dealer said trim it up but thats not the real issue he should have mounted it higher - cav plate should be 1 1/2" to 2" above the hull bottom with that prop its a good prop - not exact as each hole is 3/4" but at least 1 1/2. you can measure it with any straight edge, wood or PVC

i agree - motor mounted too low

i used to have a maycraft 19 cc with a 4 stroke that came with straight cable steering (not a NFB). If the engine was all the way down when you took off you could FEEL the torque of the engine and if you let go of the wheel the boat would turn almost instantly. While running, if you trimmed the engine until the cav plate came out of the water, you could feel that torque just release from the steering wheel.

Moved engine up, 100% better..........added in a NFB helm and problem completely gone.


If you have a teleflex cable steering, you can actually just get the NFB helm and swap them easily. The old cable will go right back into the new helm.