BanoDyne - Engine Mounting Photos Optimax Mercury

Re: BanoDyne - Engine Mounting Photos

Most of these big motors are used in speed applications with high rake props. A highly raked prop will interfere with the tab. I have actually trimmed off part of the tab to prevent this. If the tab is not used then a smooth cover should be used in it's place to prevent turbulence from the open hole.

On a counter rotating twin the engine torques counter each other but it does stress the steering linkage and a properly set up tab will help prevent this. It is necessary to know how to rig it.

On a single engine boat without some sort of tab the boat will be much harder to turn in one direction as opposed to the other even with hydraulic steering. I have been there done that.

With a surfacing application a tab is used on the lower skeg. The newer lowers have it built into the casting. They are often added to the older or converted lowers.

http://www.bobsmachine.com/Products/engine_torqueTamer.cfm

If your boat is difficult to turn in one direction and the trim angle does not fix it then you need a tab. I would not leave home without one. Just my opinion.

I do not use high rake props because they cause the stern to dig deeper which is not what I am looking for. I want to be quick on plane with as level an attitude as possible. So, I can use the tab. My tab is set to max deflection for the slow speed stuff.

FLUSH MOUNTED AIRGUIDES:

The guts from the flush mount airguides are different from the recessed ones. They are imminently repairable. What are the symptoms?

jim

 

Re: BanoDyne - Engine Mounting Photos

Disagree. My Optimax 150 did not have a trim tab, same like yours Mark. Ran a cable steering set up. No problems turning the boat from left to right. There was no difference at all. It was not harder one direction from another. Same goes for the Airguide subject with the pressure tubes on either sides. I ran 2 Airguides on separate tubes. One on the left and one on the right. Both registered the same on my 18' in the turns. And that was during a lot of swivel type speeds. Mark check the photos that you have of my transom and motor to confirm the above.

Greg

 

Re: BanoDyne - Engine Mounting Photos

I'll say it again slowly. IF your boat turns harder in one direction, then you need a tab.

jim

 

Re: BanoDyne - Engine Mounting Photos

Speedometers:

Palo Alto speedometer can refinish the faces. I have not seen an instrument like that for sale in a while. Those instruments were made in America and are all metal. They come apart fairly easily and it is obvious how they work. I would spray the mechanism with electrical cleaner and see if they will free up. You can work the mechanism by hand and see the problems usually. It sounds like there might be a restriction in the air fitting. You should be able to see that in the little fitting on the back of the instrument.

If you still have the old ones, you might use a part out of one. Sometimes the little bellows leak, they can be repaired too. Since it works, but slowly, I think you can repair it.

jim

 

Re: BanoDyne - Engine Mounting Photos

Most Mercury V6 Blocks have not use tabs for a few years. Not real sure why. I would guess for multiple reasons. One being prop interference. Two being the advancement in no kickback steering. Three and the most important cost reductions. I just rebuilt a lower unit for a friend who had a 2000 EFI 150hp Saltwater Series and it had a tab. Sometimes big companies do wierd things that normal people aren't suppose to understand. Rolling Eyes

Edd

This is my answer to all those tubes running from the back to the front the boat and getting plugged. The only drawback is in fast current.


http://www.livorsi.com/catalog/gps.htm#GPS_SKI

 

Re: BanoDyne - Engine Mounting Photos

Daniel

I've said it before but it is worth saying again. That picture of your dash with the water and hills in the background remains one of my favorite Hydrodyne pictures of all time. I wish you would make it into a website header.

There is nothing I love more than a good debate. This trim tab stuff is very interesting. As are discussions about props. Most boat owners use whatever the boat dealer puts on the boat. My oldest brother routinely complains that he is uncertain as to whether he has the right prop on his 17' Glastron (135 Optimax) but I have no answers for him and neither does the boat dealer. I guess I should get him hooked up with one of the experts on this website.

So - in order to extend the debate - has anyone heard of outboard engines being installed slightly off-center in order to compensate for torque steer? Some aircraft engines are mounted at an angle to offset left turning tendencies under high power/high angle of attack, I'm told. Just curious.

MarkBano

 

Re: BanoDyne - Engine Mounting Photos

I have noticed that some skegs appear to have a slight bend in them. At first I thought someone smashed into something, but there isn't any sign of damage. Maybe this is a calculated permanent trim tab that would work no matter how far out of the water the prop is (until you go airborne)? Any one else notice this? I believe it's only been on the bigger motors that I have noticed this. I don't recall if mine looks like that or not, but I will check.

 

Re: BanoDyne - Engine Mounting Photos

Yamaha uses a concave skeg on their VMax hpdi 3.3L motors to reduce torque steer. I will say this, on a twin rig without counter rotation it creates some interesting handling issues.

 

Re: BanoDyne - Engine Mounting Photos

The mercury sportmaster lowers have a cast in torque tamer. The late model CLE's did too. They are low water pickup lowers meant for surfacing applications.

I believe the cases that are meant for multi engines do not have the cast is tab. I personally have only seen tabs for right hand rotation.

There are a multitude of different applications out there, so one rule can't fit all.

I looked in the merc parts breakdown and on the 3 liter dfi it only shows a smooth anode for the hole where the tab normally goes. My parts guru is out of town so I can't check and see if there are any tabs that will fit the 3 liter.

In the high performance boat arena there have been some failures on the one bolt that holds the seastar to the tiller. Engine torque puts a lot of strain on that bolt. It would be prudent to check the torque on that bolt often, and replace it often on the big engine applications. The Mercury bolt seems to be preferred over the seastar bolt in the performance world.

edit, I have seen engines mounted off center.

jim