Motor Mount Mods for VS1

[mtgoat]

Here are the modifications I've made to this motor mount for my VS1 build.

In order to get the steering pivot closer, I slotted the pivot hole and countersunk the holes where the assembly mounts to the transom.

Since this mount is a bit heavy, I cut out some unnecessary metal with a jeweller's saw.

The pivot is now 3/4 inch from the transom. By comparison, an un-modified Dubro mount is 1-1/8 inch. This puts the center of the pivot about 3/8 inch forward of the rear of the sponsons.

[eboat]

Just a question

Why is everybody moving the pivot center farther ahead ??

I always thought it was better if it would pivot right at the end of the sponson

How far ahead is enough ??

[properchopper]

Here are the modifications I've made to this motor mount for my VS1 build.

In order to get the steering pivot closer, I slotted the pivot hole and countersunk the holes where the assembly mounts to the transom.

Since this mount is a bit heavy, I cut out some unnecessary metal with a jeweller's saw.

The pivot is now 3/4 inch from the transom. By comparison, an un-modified Dubro mount is 1-1/8 inch. This puts the center of the pivot about 3/8 inch forward of the rear of the sponsons.

That's exactly what I was originally going to do with the same mount [slotting]until I got crazy with the wood saw.

[properchopper]

Just a question

Why is everybody moving the pivot center farther ahead ??

I always thought it was better if it would pivot right at the end of the sponson

How far ahead is enough ??

According to some older posts on another forum as well as the VS-1 instructions, placing the pivot back causes oversteer[ read: dreaded spinouts]. Further forward induces understeer, which might be better in tracking the turns. We'll see !

[mtgoat]

That's exactly what I was originally going to do with the same mount [slotting]until I got crazy with the wood saw.

That's funny, I had originally considered doing something like what you did on your VS1.

[Grimracer]

True enough

Rule of thumb

Pin past the back of the sponsons.. Over steer
Pin = with the back of the sponsons.. Neutral
Pin in front of the back of the sponson.. Under steer

The VS-1 works best with the pin no further back "From the Transom" .600".

Just for the record.. the K+B and the OS lower units "at this time" have the least amount of lift.

In order as I know them from the least lift to the most.
K+B
OS
REK
Lawless
Hyperdrive"angledrive"

I really do not know that much about the old bullet drive (I have not seen one for years now)

Grimracer

[eboat]

True enough


Just for the record.. the K+B and the OS lower units "at this time" have the least amount of lift.

In order as I know them from the least lift to the most.
K+B
OS
REK
Lawless
Hyperdrive"angledrive"

I really do not know that much about the old bullet drive (I have not seen one for years now)

Grimracer

When you say the leg has alot of lift what gives it the lift ??

Is it how wide the leg is so something with a narrower profile is better ??

[properchopper]

I believe, by looking at the lower leg, that the wide profile acts like a trim tab. Now that this issue's been raised I'm definitely having some troubled thoughts about using the Angle Drive, but I'm committed by now. I'm definitely going to arrange the internals to allow maximum rearward CG adjustments & will hub-cut the props to minimize lift.