Redoing mold

When you say x you mean extra long like 25 inch shaft ?

I converted my own boat that was an old 16 inch when it was mad then someone packet it to a 20 inch and cocked it up completely and the motor was to high .
It had holes every where and looked discusting so I did a whole transom cut off and complete rebuild and made it to take a 25 inch motor .
My reasons were to get the motor up in fresh air so it wasnt sucking salt laiden spray into the cowl and into the motor , The other big plus is in a following sea it dosent dissapear under the stern wave that rolles into the back of the boat when you are in real rough water and only able to go quite slow .
Its really scary stuff when you have a vee 6 Merc and theres only the top of the cowl sicking out of the water at odd times and you are 20 miles off shore punching a head wind , like it took 45 minutes to get to the spot but 3 and a half hours to get home again .
Something i feel some people are forgetting is the extra leverage thats going in the transom so if you are rebuilding to accomidate a 25 inch motor then make it just that little bit stronger specially at the top of the ransom !!! The bolting pattern is the same as the 20inch but the actual base size is a fraction longer so thats another thing to watch for to . Yes they are becoming more and more popular even down to the smaller sizes .


AT the other end of the scale some racing motors can be down to 12 inch shaft as they chop the bottom of the centre section of the motor down , to do with getting the centre of gravity lower to stop roll when going round corners real fast and help to minimizing airdrag from the engine cowl .
Have a look at circut racing motors them look at off shore racing motors . Mercury have all the interesting stuff . Take a look at the shape of the gear case as well while you are there and note the differance to a standard motor !!Theres lots to learn and remember !!

 

For this size boat stick with a 20" transom, finding an extra long OB in this HP range won't be easy.

 

Have you desided on a motor size yet ?? 16 Foot could take a 90hp or even bigger depending on what goes inside and what sort of water you want to use ithe boat in .
Plenty of 90hp x 25 inch Yamahas or almost any brand for that matter !!
If your a bit of a speed freak 125 or 135 with 12 inchs step back and a jacking plate would be scary when its set up properly !!Id even go so far as to use hydralic steering with all that !!
Buy a bunch of hats cause you gonna loose a few !!!

 

The 90's and bigger have a 25" option, under that you don't, so why limit your options to something 90HP or bigger when 20" is the normal length for a boat of this design and it can get by with a smaller than 90HP motor very well.

 

Wow, that looks just like the boat I'm replacing the floor in!

It has rolled edges, and a rub-rail riveted to it on the outside. Small stringers with a floor taped to the inside of the hulll. Gas tank in the belly, near the stern.

Best wishes on a great mold and boat!

-TH