Converting long shaft to Ultra long

Oct 28, 2013
678
Hunter 20 Lake Monroe
We just bought a one year old Tohatsu 4 hp 4 stroke for our hunter 20. We have a 2 year old Nissan 3.5 hp 4 stroke that works great but the Captain has short arms and she has all sorts of issues spinning the motor around for reverse. I am thrilled that Cindy sails with me and if a few hundred bucks for a different motor makes her happy then it was a deal.
That said. We both see the need for the longest shaft length we can get as when we are in following waves and one of us goes forward the prop cavitates. We were stuck with the long shaft on the 3.5 but the 4 -6 hp can be converted to a ultra long 25" shaft length.
I contacted customer service at Tohatsu today and they sent me the list of parts that I will need, which are:

3H6610120M drive shaft housing gasket
369Q611101 UL extension housing
9161130625M bolt
9401130600M washer
9152E30825M stud bolt
9401030800M washer for stud
9301030800M nut for stud
369651200M Water tube UL
369643030M driveshaft UL
369660142M cam rod UL

He said the following concerning the conversion,"The conversion can be done. The power head has to be pulled up to change the water tube and shift shaft. You will also have to pull the lower unit apart to replace the drive shaft. The other issue is there is no kit so you will have to get all the parts individually."
I took the parts list and just sent off to Tahatsu parts online to get the price for the required parts. Looking at the parts breakdown it seems to be a very straight forward job not requiring much more than would be required to change the impeller.
I know that I could get a 6 hp sailpro new but 1, we don't need 6 hp, 2 the internal tank works very well for our needs, 3 and assuming I can sell our 3.5 hp for what it is worth the swap has only set us back 250 bucks plus the parts to do the conversion. So for less than a grand we will have a one year old ultra long shaft 4hp with the internal tank that we can convert to a 6 hp should the need ever arise.
I will post updates as this project progresses. Of course if the parts are 500 bucks then the project just died before we ever got started.

Sam in IN, getting ready for next season already!
 
Feb 20, 2011
8,048
Island Packet 35 Tucson, AZ/San Carlos, MX
I've got the Nissan 4 long, and wondered about this conversion myself. Looking forward to your reply from Nissan/Tohatsu/Mercury.

Thanks!
 
Oct 28, 2013
678
Hunter 20 Lake Monroe
Still waiting to hear back on the cost of the parts but Tohatsu got back with me and said that is not a difficult job at all to do. Just hope the parts are somewhat reasonable as that will be what really determines if I move forward with this mod.

Sam in IN
 
Oct 28, 2013
678
Hunter 20 Lake Monroe
Well I just got some prices

3H6610120M drive shaft housing gasket 4.90
369Q611101 UL extension housing 122.29
9161130625M bolt
9401130600M washer
9152E30825M stud bolt
9401030800M washer for stud
9301030800M nut for stud
369651200M Water tube UL 16.61
369643030M driveshaft UL 114.09
369660142M cam rod UL 15.81

It looks like 300 bucks will cover the cost of the parts. These prices were from Boats.net which had a easy online look up of the parts I needed. I will keep looking and see if I can do better elsewhere.

Sam in IN, crunching numbers.
 
Sep 20, 2014
1,328
Rob Legg RL24 Chain O'Lakes
My 86 lbs thrust trolling motor has a 36" long shaft, plenty of length to be a few feet below the boat if you want. I just converted to electric and its wonderful. Having previously had a 4hp, I would put the performance somewhere between a 3 and 4 hp. It has more torque than the 4hp, but a slightly slower top speed. I love the fact that it turns on at the flip of a switch. Much lighter than a gas engine, so it is very easy to tip in and out of the water. But the best part is that it is dead quiet. On days when there is no wind, you can still ghost along without any noise or smoke. It brings some of the same qualities that sailing brings. Two 100 AH batteries and motor (on Ebay) runs less than 400 bucks. To me for anyone needing 4hp or smaller, it seems like a no brainer.

ON Edit: I just looked back and saw that you sail on Lake Monroe in Indiana. I have sailed on that lake and definitely would recommend going electric with your 20 foot boat. Your boat weight is the same as mine, and knowing that lake, it is by far the best solution. The batteries would run you up and down the full length of that lake several times. I figured out that if I run at a setting of 3, I could run for 11 hours straight before I would need to charge the batteries. On my boat, that means running along at just over 3 knots for 11 hours. Wide open runs almost 5, which it should do for 2 hours.
http://www.ebay.com/itm/New-86lbs-F...or-36-Shaft-/271488313008?hash=item3f35f6e6b0
 
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