Why no trim on inboards?

[JB-FOOT]

Trim definitely adds a level of complexity to the system. I'd settle for trim tabs. Any monkey could pull that off. And why Tige was ever allowed to patent it is beyond me.

I know a number of guys who added Bennets to old MC v-drives when they had the porpoising issues. Problem solved.... for like $300.

What (I think) is happening here is that we are all forgetting about the three different types of hulls here...

1. I/O hulls (BASIC) are straight back and thus are Neutral allowing the boats trim system (prop moving up and down at an angle) to work for raising and lowering both the bow and stern.

2. Inboard Hulls (BASIC) are not straight, but have a concave angle at the stern , which in turn keep the bow down by lifting the stern....this is what make it difficult to sink the stern and why we need to add ballast and or use the Wedge to PULL the stern down...Also, trim tabs on a basic inboard hull would only work to FURTHER lift the hull and FURTHER lower the bow in the water and cause more drag.

3. Tige' Inboard Hulls (advanced/different than other basic inboard hulls) are CONVEX at the back and cause the stern to NATURALLY sink and the Bow to RISE.....so the trim tabs on a Tige' Hull actually work more like the I/O hull and can lower the bow by lifting the stern...and so that hull is very trim sensitive. Not as much as an I/O, but radically different than your standard Inboard hull...

I could write about 15 more paragraphs about this but my fingers are getting tired...

The point is that trim tabs work very differently on different style and shaped hulls...and what works on one style DOES NOT WORK on another style...

Edited April 25, 2013 by JB-FOOT

[jk13]

OH WOW WOW WOW!!! I hope this is a joke! If not, I need to see this train wreck...

Not a joke. Someone ripped the underwater gear off and crudely glassed an I/O mount chopped off another boat.

Course it was on CL TWO YEARS AGO when I typed that and when I searched for it again back then it was gone.

[bamabonners]

Searching the archived threads I see..... Lol

[formulaben]

Sorry...just hoped that someone might still have the pic.

[SmoothWaterMan]

I was reading the high speed topic for the new engine and got to thinking...Why don't any inboard manufacturers create a trim system for an inboard boat? As I see it, that would add a new dimension to these boats that some people might find appealing. I understand that this adds a level of difficulty to the engineering (universal, drive dog, hydrolic trim, and beefy strut support) , but my question is: Is it possible? And would the trim increase speed and/or hours per gallon ratio? I would think you would gain some promosing characteristics of an I/O drive with the ability to change the thrust angle parallel or better. Likely this would be used when not doing sports behind the boat since it would produce a propwash for the skiier, but that would be up to the driver. Has anyone ever heard of a mod like this being done. This is purely accademic, but interesting all the same.

Similar to this but mounted under the boat instead of behind the boat

Jimmy, they've done this....

.... it's called an I/O

Here's a better photo - bottom of this page :

http://www.boatdesign.net/forums/powerboats/efficiency-surface-drives-surface-piercing-propellers-2981.html

Edited April 27, 2013 by SmoothWaterMan

[Jimmypooh]

Jimmy, they've done this....

.... it's called an I/O

Here's a better photo - bottom of this page :

http://www.boatdesign.net/forums/powerboats/efficiency-surface-drives-surface-piercing-propellers-2981.html

I/Os have the prop behind the boat and the engine mounted with the output shaft toward the stern. I was thinking still v drive but mount the prop under the boat with a pivot point.

[formulaben]

Sounds like a pod drive.

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