I have a small aluminum mudboat set up with a couple options but I have questions.

I like to use what I have on hand,not much money to spare these days.

14x3 riveted hull that the bottom was replaced with a 3/16" sheet.Its heavy.
currently has a 13hp kohler command direct drive.

prop for a 18hp that was turned down for a 16
strut is about 18-20 degrees
boat travels at 20mph in deep water,about 23 in shallow,no complaints there.

I have a very small 10 hp tractor manual transmission with a cute dual disc manual clutch(fully enclosed unit) with ratios as follows.

1st gear 5:1
2nd gear 2:1
3rd gear 1:1
reverse 2:1

questions are should I?

use 3rd for forward 1:1 with a 2:1 reverse propped for the correct hp?

use 2nd gear for forward making both directions 2:1?

what will perform best in thick muddy situations?

If I can stay around the 20mph mark that's great so Im leaning toward the 1:1 forward idea.

But will a correctly propped 2:1 forward out perform the 1:1 ?

I also will be using a 10hp diesel engine.It will outperform the 13 kohler.

Diesel makes 20ft lbs at 1500 rpm,at 3600 rpm the ft lbs drop to 19,That is way more than the 13 kohler makes at lower rpms.Kohler at 3600 makes 21 ft lbs.......which it will never see.

Will adding a 2:1 multiply horsepower?I think it onlu multiplies torque.Not sure.

I have only had small inboards direct drive.Been stuck a million times where even 2:1 reverse would have saved me.


Thank You in advance

Whats your opinions