Small boat and Titanic same problem!

[hardchines]

For those that have seen my post called "small boat big big project", my first shake down cruise last year was a success, but not without exposing problems and items that just need updates or modifications. I have to address list items before my second shakedown cruise this year, at this point I have 25 line items to address, some items are simple such as adding a small table/shelf close to lower helm so I can reach my coffee or binoculars without stretching to my reach limit, the item I am working on now is a little more involved but very important, I need to increase helm authority at slow speeds and in reverse!

The Titanic had a problem just like mine, not enough rudder, in some respects worse then mine. Titanic had one rudder behind the center shaft only, one problem with this that you never see on the documentary shows, is that the center shaft only turned when the ship was going forward using the other shafts, no reverse rotation ever, center shaft was a steam turbine that used the waste steam from the largest steam piston engines ever built to date! Ok so my giant 26 foot yacht has one small Mercury alpha gen 2 outdrive, fine for control at higher speed then I cruise at but not good at very low speeds such as mine. first I have allot of wandering at low speeds unless I put my large trim tabs down, then tracking is fine and no detectable speed loss as a result of tab position as I travel SLOW! I went threw 70 locks last year, I found as I approached the lock walls at slow speeds I had very little helm control and a long delay of what control I did have even with helm hard over.

The plan to fix the problem, first I figured I would just buy a set of Wander fins or Uncle Norms Orca fins to remedy the problem, they get good reviews for fixing bow wander and they help get your boat on plane faster! They are small so they can wok at high speeds. They are a good fit for most normal IO boats but my boat is anything but normal, the original empty weight of the 2667 was about 5400 lbs dry, 6200 with full gas and water, I am tipping the scales at just north of 8100 lbs wet but completely empty, I carry allot of equipment and supplies that adds considerably to this number. Heavy slow and a tiny little rudder, I gotta watch for ice bergs! I have decided to build my own set of flanking rudders (normally in front of props) for my out drive, similar to wander fins but much larger in every respect, I think this will work fine as my normal cruise speed is 6.1 MPH and max speed of around 9 MPH, I hope it eliminates bow wander so I can stop dragging the back of the boat with the trim tabs ( may get me up to 6.2 MPH )they should give me allot of helm at slow speeds and should take some load off of the hydraulic autopilot pump! Because of their size I am making them out of 1/4 inch high grade aluminum plate, sorry for all the verbiage but I am long winded! photos to follow soon

[km1125]

Max speed of 9? Do you ever get on plane, or is this just in the canals?

If you never get on plane, what about a different prop? I use a "high thrust" prop on my outboard, which is also used on a lot of 8-10K lb sailboats for better maneuverability at the slower speeds.

[Viper]

Has anyone checked to ensure your swivel/steering pin at the top of the gimbal ring has no play? Your drive should have very little play from side to side when moved by hand without actually moving any of the steering hardware. If there is play there, you will get exaggerated wonder when underway at slow speeds. Play in the steering cable and the rest of the steering hardware will all contribute to the wonder as well. Do you have a flat or fin shaped anode on your cav plate? A fin type properly adjusted will counteract the sideways thrust due to prop rotation which can also contribute to constant heading correction. Are you propped right? What I'm saying here is make sure your OEM hardware is in good condition and that it's set up properly rather than throwing something on it to try and counteract wear and tear on the original equipment. If it is worn, it'll just get worse not better no matter what after market item you put on.

I'm not a big fan of adding anything to drives for a few reasons:
- anything that is bolted through the drive means holes that WILL increase corrosion. Adding more stainless steel (bolts) in contact with the drive will also increase corrosion. For those that are not bolted through, they are not electrically connected to the drive which is a must if the item is to be properly protected by the anodes on the drive.
- The drive casing is a specific aluminum alloy blend. Anode metallurgy takes this into consideration. If you're going to add a dissimilar aluminum alloy in close proximity, I'd keep an eye on your drive and anodes to ensure the addition of the new alloy doesn't change the electrical potential that's protecting your drive.
- adding anything on to the drive such as fins or stainless skegs, etc. increase the potential of a major casing failure should it get hit. These areas are designed to break away when hit, and can be easily repaired. When hardware gets fastened to these areas, they tend to cause un-repairable casing/drive damage after an impact.

[dsolo]

I am sure Viper is giving good technical advice above. But I struggle with the same issue. I own a 405 MY and have control issues when under windy conditions. I just don't feel the control. My slip is 16 feet wide and the approach is 50' wide. My pal is 43'. I am stern in. Any wind over 10 knots is a challenge. Northeast winds are killer. I would like more bite and positive reaction at idle speeds.
If you have determined your acceptable cruising speed of 6-9 knots you have plenty of options. I haven't figured this out yet. Hope to with more time on lake.

[Viper]

Source of the post.....I own a 405 MY and have control issues when under windy conditions.....Any wind over 10 knots is a challenge.....I would like more bite and positive reaction at idle speeds.......

Most of us struggle with the same thing. All you can do is take measures to overcome varying conditions. You're basically a big wall that the wind is pushing against. The bigger the surface, the more the impact wind will have. Add current, anxiety, tight quarters, etc. and it can be a challenge for sure.

Thrusters help, along with steering, increased rpm, and friends at the dock. More bite is good to a certain point but it can also be a challenge at times in tight quarters as small adjustments are doable but not without some forethought. I've been on relatively small boats for the sizes of diesels installed and I can tell you, they have a lot of bite and can be scary docking aft in since a momentary touch of the shifter swings you three feet. It's great in windy conditions but is the opposite and challenging when it's calm if you're not use to it.

Practice practice practice!

[km1125]

Source of the post I am sure Viper is giving good technical advice above. But I struggle with the same issue. I own a 405 MY and have control issues when under windy conditions. I just don't feel the control. My slip is 16 feet wide and the approach is 50' wide. My pal is 43'. I am stern in. Any wind over 10 knots is a challenge. Northeast winds are killer. I would like more bite and positive reaction at idle speeds.
If you have determined your acceptable cruising speed of 6-9 knots you have plenty of options. I haven't figured this out yet. Hope to with more time on lake.

When docking in such conditions, you may have to rely on gracefully using pilings as pivot points.

[dsolo]

Agreed. Practice setting RPM to wind conditions and keeping boat straight. That is my first step. I selected a slip to accommodate the pervailing winds of Southwest, haven't seen them yet. All north to northeast. thanks

[hardchines]

KM1125 I am maxed out on prop in diameter and pitch, I use the lowest pitch prop made by Mercury , and the diameter is max on a gen 2 outdrive, 10x16, that all works fine, the engine puts out a whopping 43.5 hp @ WOT, this is a mild V hull 18 degrees at transom, many small V bottom heavy boats do not track well a slow speeds, usually real bad with out-drives and seating aft. I really just need much MO rudder, my cruise speed is 6.1 mph, more then that speed is emergency power only, going through a narrow bridge with a stiff tide against you, I can triple my fuel burn to go .9 mph faster!

[hardchines]

Viper, yes I am the mechanic on the yacht, the gimble I installed is very tight as is the hydraulic ram and all connections, you can not budge the drive left or right. one must remember that out drives are made to work at all speed ranges in most any hull, so they are a trade off in all areas, if they were installed on high speed boats only they would be tiny pointy race looking units, if installed only on 6 mph boats they could and probably would be large to give good low speed control, my fix is to add the rudder area that is just not needed in the average install. Impact damage could be a problem but with a max cruise speed just over 6 mph it should not be a case splitter, but if it did the 2 to1 reduction gear case I use is on every merc 4 banger small boat, they rarely fail as they handle little hp so the demand is low as is there price! I use a new Merc prop , all as new. thx for the suggestions!!

[hardchines]

Well I built my duel rudder add on and it is installed, I think it should do the trick as far as low speed rudder authority, will it help with bow wander, that remains to be seen!