Outboard motor shaft lenght

[Transplanted Sportsman]

I need help in detrmining how to measure an outboard motor shaft lenght, I have received conflicting info on how to properly measure it so any help from the guru's or people with knowledge on this topic would be greatly appreciated, I was told I have an outboard with a shaft that is a little too long for my Riverhawk and I need to confirm that before going on a search for a small outboard with a shorter shaft, thanks in advance!!

TS

[bfish]

My old riverhawk 12' required a short shaft (15") motor. If you don't want to change motors, sometimes a jackplate can be used. For another old boat of mine (Gheenoe) I used the mini-jacker which gave me about 3" of extra height.

[SalmonDaze]

How much "too long?"

What kind of performance are you trying to get?

I can see purchasing a new engine if too SHORT (blades in the water really help move the boat).

But . . . a bit too long? You will have to run that motor a long LONG time before you even approach efficiencies needed to offset the cost of a new (or used) motor.

[Transplanted Sportsman]

Originally Posted by bfish

My old riverhawk 12' required a short shaft (15") motor. If you don't want to change motors, sometimes a jackplate can be used. For another old boat of mine (Gheenoe) I used the mini-jacker which gave me about 3" of extra height.

Bfish, I have a 12' Riverhawk as well and the motor is a Briggs and Straton air cooled 5 HP this motor was used by a Walleye fisherman as a kicker for trolling, I guess I will be doing the mini jack plate if the difference is only a few inches, it will be cheaper than another motor that is for sure, where do i go about finding one of these? are they easy to install or do they require a pro to do the job?, thanks for the response!!

[Transplanted Sportsman]

Originally Posted by SalmonDaze

How much "too long?"

What kind of performance are you trying to get?

I can see purchasing a new engine if too SHORT (blades in the water really help move the boat).

But . . . a bit too long? You will have to run that motor a long LONG time before you even approach efficiencies needed to offset the cost of a new (or used) motor.

Salmon, I do not know for sure but my friend said it looked too long, his point of view was that the longer the shaft the more drag it created since too much of a shaft extended down from the bottom of the boat to the propeler and he said I would get better performance if I trim it up, but reading the manual it adviced against doing this and they recomended to have the motor as vertical as possible, so I need to know how to measure this correctly to find out if I have either a 20 or a 25 inch shaft then see what could be the best thing to do, although the mini jack plate sounds to be the answer if the difference is only minimal, I know what you mean about the propeler being in the water, that was funny there man!!, thanks for your reply as well!!

[bfish]

Pretty easy to install. Drill holes in transom. Bolt down jacker (using 3m 5200 sealant), then re-attach motor.

I think I got mine at either Bass Pro Shops or Cabelas.

You can also clamp a 2x8 to the transom so that the board sticks up 2-4 inches above the transom. Then attach your motor to the elevated part of the board, especially if you want to test fit to see if the jackplate will give you enough increase in elevation.

[Transplanted Sportsman]

Thank you so much B fish, I will start looking for one this weekend!

[tkwalker]

Originally Posted by Transplanted Sportsman

I need help in detrmining how to measure an outboard motor shaft lenght, I have received conflicting info on how to properly measure it so any help from the guru's or people with knowledge on this topic would be greatly appreciated, I was told I have an outboard with a shaft that is a little too long for my Riverhawk and I need to confirm that before going on a search for a small outboard with a shorter shaft, thanks in advance!!

TS

Okay all Gheenoe and RiverHawk transom heights are the same ... 15 inch ... The rumour is the now owner of river hawk was a partner of Gheenoe ... the Gheenoe owner/designer was a bad businessman ... wanted to open a plant in Ga.(Gheenoe based out of FLA. ) His partner did open the plant change a few dimensions .. and screwed Ghennoe .. Renamed River hawk ... Just Rumour ?? Don't have a clue on facts ...

But ... To check an outboard for drive shaft length is simple ... All of the above examples are good ... But if confused ... this is what you do ...

All the lower units on all outboards are the transmissions ... They are just bolted to the exhaust housing .. That is the long unit that drops down from the motor /power head ...

Shaft heights are measured from the clamp bracket ... Where it sits on the transom to where the lower unit bolts on to the exhaust housing ... So measure from the transom to the mounting halves where the lower unit bolts on to the exhaust housing ... Call me if you have questions ... 615-347-8277 ... <'TK><

Now Jack plates ... They are okay in some applications ... as far as shallow waters ...say the Caney ... creates problems ... !. you have a mass of motor that you have to constantly be pulling up or down for shallow drive ... also a high profile over the transom to manipulate for control ... I am speaking from experience ... Especially fighting this in a high current condition ... ... jack plates are good .. but not for Creeks, and shallow water applications unless you are young and strong ... <'TK>< Hope this helps ...

[Transplanted Sportsman]

Originally Posted by tkwalker

Okay all Gheenoe and RiverHawk transom heights are the same ... 15 inch ... The rumour is the now owner of river hawk was a partner of Gheenoe ... the Gheenoe owner/designer was a bad businessman ... wanted to open a plant in Ga.(Gheenoe based out of FLA. ) His partner did open the plant change a few dimensions .. and screwed Ghennoe .. Renamed River hawk ... Just Rumour ?? Don't have a clue on facts ...

But ... To check an outboard for drive shaft length is simple ... All of the above examples are good ... But if confused ... this is what you do ...

All the lower units on all outboards are the transmissions ... They are just bolted to the exhaust housing .. That is the long unit that drops down from the motor /power head ...

Shaft heights are measured from the clamp bracket ... Where it sits on the transom to where the lower unit bolts on to the exhaust housing ... So measure from the transom to the mounting halves where the lower unit bolts on to the exhaust housing ... Call me if you have questions ... 615-347-8277 ... <'TK><

Now Jack plates ... They are okay in some applications ... as far as shallow waters ...say the Caney ... creates problems ... !. you have a mass of motor that you have to constantly be pulling up or down for shallow drive ... also a high profile over the transom to manipulate for control ... I am speaking from experience ... Especially fighting this in a high current condition ... ... jack plates are good .. but not for Creeks, and shallow water applications unless you are young and strong ... <'TK>< Hope this helps ...

TK, I do not know if there is some truth to the statement about the Riverhawk birth, but let me tell you they have by far the worst customer service of any company I have ever dealt with, I bumped the drain plug of my boat with my riding mower as it hangs from the shed a couple of years ago and it bent it so it is a bit of a pain to take it out, I have called about 3 or 4 times, spoke with Mr Bob, left voice mails, emailed him as per his request and I have yet to hear back from him, maybe I should say I would like to buy a boat instead of just a drain plug to get his attention, the 3 dealers listed for TN were not much better, the one I bought the boat from said I needed to buy it from the factory, and the other two never responded to my emails and phone calls so their service really stinks!
I did the measurment the way you describe it and it measures right at 18 inches from the mounting bolts to the bottom of the cavitation plate, I did not see where the halves meet or any bolts near the cavitation plate, I guess I need to really take a good look at it, I did this on my way to drop daughter to school so I was on a hurry, and I know what you mean about lift/tilt the motor it is hard in my case because the handle is so far back and down and it is hot all the way around so I try not to do this!!, thanks for your help!

[tkwalker]

Originally Posted by Transplanted Sportsman

TK, I do not know if there is some truth to the statement about the Riverhawk birth, but let me tell you they have by far the worst customer service of any company I have ever dealt with, I bumped the drain plug of my boat with my riding mower as it hangs from the shed a couple of years ago and it bent it so it is a bit of a pain to take it out, I have called about 3 or 4 times, spoke with Mr Bob, left voice mails, emailed him as per his request and I have yet to hear back from him, maybe I should say I would like to buy a boat instead of just a drain plug to get his attention, the 3 dealers listed for TN were not much better, the one I bought the boat from said I needed to buy it from the factory, and the other two never responded to my emails and phone calls so their service really stinks!
I did the measurment the way you describe it and it measures right at 18 inches from the mounting bolts to the bottom of the cavitation plate, I did not see where the halves meet or any bolts near the cavitation plate, I guess I need to really take a good look at it, I did this on my way to drop daughter to school so I was on a hurry, and I know what you mean about lift/tilt the motor it is hard in my case because the handle is so far back and down and it is hot all the way around so I try not to do this!!, thanks for your help!

I don't remember what model or make of motor you had but for most of them this application should apply ... Look above the large anti cavitation plate about 3 inches there should be a flange there ... If it is a Merc/Tahatsu/Nissan you may not see but one bolt ...

Look at the the pic of the Nissan above .. See the Anti cavitation plate is even with the bottom of the boat .. but look above the Anti Caviation plate and you will see the flange I am talking about ... That is where the Lower unit bolts on and that is where you measure to .. It should be 15,20 or 25 inches to that point +/- 1/2 inch (These are the standard factory heights ) ... (PS I have a River Hawk also) <'TK><

[Transplanted Sportsman]

thanks for the info TK, I will be checking this out later tonight, your description makes it easy to understand!!