motor shaft length vs transom?

[cmdrost]

Anyone have a motor with a 20" shaft on their bayboat? Been debating the topic with a friend. I see several new blackjacks with the new yamaha SHO engine. Did blackjack shorten their transom or does it work with most boats? Just have to mount the jack plate lower?

[LaAngler]

it's the same hull i'd bet but with a 10-12 inch set back plate mounted for a 20 inch, pocket transom, once you find the sweet spot on the jackplate it's fine & works nice with shallow holeshots.

[PUREBAY2200]

Can't u lower/ raise the mount height with a jackplate?? I don't know much bout this just wondering.....

[I make oil]

The boats I saw using the short shaft motors use a Hyd Jack Plate. The problem is if you have the motor down and trim all the way up you hit the cowling on the tansom. The boats I have seen factory rigged that way have a sticker on the console telling you not to do it. But S**t happens. Damage 1 cowl and see what that sets you back. Also hopefully you don't damage your transom or back deck. I understand that the SHO's will come in long shaft this year. I would just wait.

[fishinpox]

bruce is correct all you need is a farther set back i have 2 buddies in florida runnin 250 shos on bayboats with a 10" jackplate they run like a sonabish!!!

[Montauk17]

Keep this in mind....the farther the motor is away from the "pad" the higher the water is coming off of it. That is why you can run a 20" motor on a 25" transom. Alot of people run 20" motors on bayboats no problem.

[Wide Open]

I Run a 20inch shaft Vmax on a bayboat. It does require a 10 in. set back, but works well !

[cmdrost]

sweet.....thats what I thought.....I had one dealer say it would work, but another person within the boating industry was telling me I was an idiot.

[flounder_smacker]

Originally Posted by cmdrost

sweet.....thats what I thought.....I had one dealer say it would work, but another person within the boating industry was telling me I was an idiot.

Well some of the older guys are used to old ways so when they see a 25" transom they say u need a 25" shaft. The big set backs do work better on the pocket tunnels as some of the boats without them have a tendency to blow out on sharp turns. Don't expect to just slap a 20" shaft on a 25" transom and perform great they take time to tune in. A hydraulic jack plate is the ticket for finding the sweet spot.

[Wide Open]

If you seem to start blowing the prop in turns the higher you raise the plate, usually a fourblade prop vs a three blade is a simple fix to the problem. I personally have not had this problem, but every set up is diffrient. It is common to lose a 1 to 3 mph with a four blade, but not on every application. some actually run faster. As stated before every setup is diffrient. The 20in shaft does perform diffriently than the 25, for instance ive run boats with the 25 that preffered to be jacked higher on the plate to obtain maximum WOT, where as my 20in shaft likes to be lifted a maximum of 1 to 1.5 on the plate to maintain maximum speed! Every thing has its pros and cons, but yes the 20 in. shaft works, and works well on bayboats set up properly.

[JDd]

Originally Posted by Montauk17

Alot of people run 20" motors on bayboats no problem.

A lot of bay boats have 20" transoms.

[Montauk17]

Skeeter and pathfinder are the main ones with 20" transoms. Majority of bay boats have 25".

[Pirate]

I know this is an old thread but I am faced with this problem. I have a 18' Trophy WA with a 25" transom. I got a great deal on a 2011 Suzuki DF140 sold to me as a 25". After bringing it to the Suzuki dealer to check hours and such I find out it is a 20" shaft. This motor still has 5 years of warranty left on it which is transferable to me. I don't know what to do, I guess I will sell it and keep looking for a 25" motor. I spoke to a few mechanics who said it could be done but there would be problems in rough water. Any suggestions would be greatly appreciated.