downside of a long shaft?

[jeff925]

I have a standard shaft 2 stroke. i can get a good deal on a 4 stroke 9.9 hp merc but its a long shaft. any downside to install a jack plate like this?

https://www.cabelas.com/product/T-H-MARINE-SUPPLIES-MINI-JACKER-JACK-PLT/3017887.uts?productVariantId=6235526&WT.tsrc=PPC&WT.mc_id=GoogleProductAds&WT.z_mc_id1=00421340&rid=20&ds_rl=1246549&ds_rl=1246552&ds_rl=1252242&ds_rl=1252079&gclid=Cj0KCQjwjoH0BRD6ARIsAEWO9DtAL9LGUU_t9xDJ1WH3rTlX17Kv5J4NAH94NX8eTlWhiTUxiEc-QGgaAvkYEALw_wcB&gclsrc=aw.ds

My boat is an 85 gregor, the transom is ok. i would have to reinforce it a little. does putting the weight farther back have any adverse effects? I have a steering console so i sit farther up in the hull anyways.


Thanks!

I need a new project for this lockdown, this might be it lol

 

[maintenanceguy]

I don't see any downside. Looks like it only sets your outboard back about 3". That wouldn't worry me.

 

[GYPSY400]

No downside to a long shaft except a slight weight penalty. If you have a 20" transom all the better. The extra 5" really makes a difference when you've got a wake catching up to you or reversing into some waves.

 

[RaisedByWolves]

Not really any downside, but there can be an upside.

On some boats I find the tiller arm to be lower than optimal with high pedestal seats. Having the motor sitting up and back makes for a more comfortable driving experience if you have added pedestal seats to your bench seat boat.

 

[LDUBS]

There are so many things I could say in response to this thread, but am biting my tongue. Too much time stuck inside I guess. :LOL2:

 

[ktoelke54]

I’ve installed one of those Mini Jackers. If you move it all the way to the top of the transom, it’ll give you about 3” lift. Not enough to convert short to long shaft. It probably would work if you braced it somehow. It is a heavy duty pice of equipment. You won’t hurt the jack plate.


Sent from my iPhone using Tapatalk

 

[maintenanceguy]

There are short shafts, very short shafts, long shafts, extra long shafts, and all manufacturers are a little different in shaft length.

But... in a 9.9hp, a short shaft is usually pretty close to 17" and a long shaft is usually pretty close to 20". A 3" rise should get you pretty close to what you want.

 

[jeff925]

thanks guys. Picked up motor yesterday. 9.9 Long shaft merc for 700 bucks. its in great condition and was just serviced in 2019 and have all receipts.

now I need to figure out what I need control wise. it did not come with any of the controls.

 

[jethro]

I had a long shaft on a boat that should have used a short shaft, it was a wild ride! When you steer at full throttle watch out, the pivot of the motor makes the boat go on it's side real quick! Although mine was a 25hp and it was on a very light 14' Grumman. You should be much better off with a 9.9hp but be careful nonetheless. I sold the motor and made the boat electric only, that 25hp was dangerous. Put me in the drink once too! Runaway boat, had no teather... what a disaster. It was May in NH, 58 degree water, could have been a casualty if not for some quick reacting lakeside home owners.

 

[jeff925]

yikes, thats scary. thanks for heads up. I set the motor on boat yesterday and it about 4 inches too low, the mini jack plate should work perfect. i little pricey at 100 bucks though but since i only paid 700 for motor it fits my budget.

i ordered the throttle and controls yesterday, should be an adventure, never hooked up a motor from scratch before but all i have is time on my hands lol.

 

[lckstckn2smknbrls]

I bought my TH mini jacker on ebay IIRC I paid $40.00ish, this was many years ago. Because of the set back on the mini jacker you can raise the motor so the anti-ventilation plate is an inch or more above the bottom of the hull. I was running mine about 2 inches above the bottom of my hull.

 

[turbotodd]

I had a long shaft on a boat that should have used a short shaft, it was a wild ride! When you steer at full throttle watch out, the pivot of the motor makes the boat go on it's side real quick! Although mine was a 25hp and it was on a very light 14' Grumman. You should be much better off with a 9.9hp but be careful nonetheless. I sold the motor and made the boat electric only, that 25hp was dangerous. Put me in the drink once too! Runaway boat, had no teather... what a disaster. It was May in NH, 58 degree water, could have been a casualty if not for some quick reacting lakeside home owners.

Sounds familiar. You outta see the numbers of 15 and 16' aluminum duck boats running around here, 70-90hp on them. I had a 15' grumman, 25hp, yeah same type thing I ran into but I caught it before it went over. Had to sell that hull, but kept the motor. Same motor on 15' war eagle, completely different. Handles and rides like a dream (at least for an aluminum boat).

 

[wmk0002]

If you decide to try it as is while waiting on the mini jacker, I’d be curious to know how the boat performs.

 

[Midwesterner]

Sea Nymph 14R - Mini Jacker - Mercury 20HP 4 Stroke long shaft.

Runs 25-26 mph on smooth water with just me. Added some plate bracing for my own sanity but I'm not sure it needed it.

I have wave wackers to go across the back that I haven't installed yet - you might want a splash shield or piece of lexan to cover the short transom cut out to block out rollers.

I did have a 20HP 2 stroke on this, the 4 stroke weighs ~25 lbs more but with the offset I was required to move my two group 34's to the front of the boat for a better balance. Still planes without issue.

Still a work in progress, floor and rear were just coated with Gluvit and topside paint with anti-slip.

 

[wmk0002]

Not really any downside, but there can be an upside.

On some boats I find the tiller arm to be lower than optimal with high pedestal seats. Having the motor sitting up and back makes for a more comfortable driving experience if you have added pedestal seats to your bench seat boat.

I actually just made some aluminum angle risers this weekend so I can install my long shaft 30hp Yamaha on my 1648 Alumacraft with a 15" transom. Mocking up the motor on it and garage testing it I believe it will be much more comfortable, especially given the setback the tilt n trim unit added to it.

 

[jeff925]

I ended up buying the mini jacker plate by TH marine. installed it today, piece of cake. very sturdy.

i need to do some clean up, cut off the ends of the bolts and removes the old controls before I set the motor on it. i installed it to get the motor 5 inches higher which puts the engine at the right height.

 

[jeff925]

Thanks for advice on here. I installed the Mini Jacker plater and got motor mounted. I ended up with 5" of lift. Another inch and a half would have been ideal (thats what she said) but i did not want the jack plate up that high. all in all pretty easy to do, very sturdy.

 

[lckstckn2smknbrls]

You could put a spacer on top of the mini jacker.

 

[Midwesterner]

Update, here is my splash guard setup. Better than nothing.

 

[lckstckn2smknbrls]

When I'm in reverse I get a lot of water coming up between the mini jacker and the hull. I'm thinking about making a deflector out of an old road sign that fits in at the bottom of the jacker.