Need Help Mounting 1986 50HP Johnson w T&T

[Goat67]

Hi All<br />I need some helpful advice. I have a 1985 Smokercraft Big Fishermen Boat with a V Hull it is 15.5 ft long. It has the original 25 HP Mariner on it. This boat is rated at 50 HP and the 25 just was not providing enogh power so I purchased the 50 HP Jounson. <br />Now the questions<br />The 50 HP needs to be mounted with bolts thru the Transom. The current motor did not mount this way so I will need to drill holes I have never done something like this, is this something a person can do or does it need to be done by the dealer? <br />If I had the steps required to do this I think I would be willing to try it.<br />So how do I determine where to drill the holes?<br />I am sure it has to do with the motor height which should end up with the cavatation plate being within 1 inch of the bottom of the boat correct?<br />What type of bolts should I use washers etc. <br />I have read to use 3M 5200 silicon?<br />And I am sure a bunch of stuff I do not even know about.<br />Any help is greatly apreciated<br /><br />Jerry

 

[Goodoleboy]

Re: Need Help Mounting 1986 50HP Johnson w T&T

Hi Jerry!...welcome to the forum.<br /><br />If it were my boat this how I would mount the motor.<br /><br />Set the motor on the back of the boat, Your gona have to have a buddy help you with that. Its gona weigh around 200 hundred pounds.<br /><br />Now take a tape measure and set the motor in dead center of the boat measure from each corner of stern over to the tilt/trim unit pick a spot thats the same on each side.<br /><br />Dont be conscerend about the cav, plate just yet. Unless its already above the bottom of boat, If thats the case you will have to find long shaft mid section. <br />If all looks well at this point, Then clamp it to the boat with a couple of C clamps.<br /><br />Now I would take a half inch drill bit and drill a hole thru the top hole on the trim unit, Same on the other side also.<br />Now go to the bottom where the sloted holes are drill again with 1/2 drill bit.<br /><br />Now caution make sure you drill in the top of the slot. If you drill in the bottom you will have no room for adjustment.<br /><br />Now I would use stainless bolts washer's and lock nuts, use silicone sealant around the bolts both inside and out.<br /><br />At this point you can raise your cav. plate if nessary. Dont go above and try to be within an inch of bottom keel.<br /><br />Tighten err down remove your c clamps. and head for your favorite fishin hole. <br /><br />Luck to ya!

 

[david18]

Re: Need Help Mounting 1986 50HP Johnson w T&T

The best thing to do is call a local dealer and ask them to do the drilling for you. They have a template plate that is clamped to the transom and guides the drill bit. You can drill it yourself by hanging the motor on the transom and marking the highest holes on the motor. Centering is very important. Mounting should be done with 1/2" SS bolts, washers and nuts. The proper way is for the bolts to go thru the transom from the inside so the nuts and washers are on the outside at the motor. Use generous silicon both inside and out. Proper height should be with the cavitation plate even with the keel or slightly higher.

 

[Goat67]

Re: Need Help Mounting 1986 50HP Johnson w T&T

Thanks guys for the info. I would like to take the easy way out and bring it to the dealer but the motor is in the back of the Bravada and the wife wants it out so I will do it my self. <br /><br />Kinda got to different opions on the height I thought I read some where on this site it should be even to 1 inch below.<br /><br />What is the effect if it mounted more than a inch below the bottom keel.<br /><br />Not that I am going to do this but I am curious,<br /><br />To High I think is a no way as it will not be deep enough to get water and will effect operation.

 

[Goodoleboy]

Re: Need Help Mounting 1986 50HP Johnson w T&T

To low in the water adds drag to your boat, slows er down ovcourse. we wouldnt wana do that now would we.<br /><br />Luck to ya!

 

[Goat67]

Re: Need Help Mounting 1986 50HP Johnson w T&T

Couple more questions<br />As I understood I should mount the bolts from the inside of the boat ?<br /><br />A washer between the head and the transom?<br /><br />What size washer as big as possible?<br /><br />Now on the other end is a washer used here?<br /><br />Maybe a lock washer?<br /><br />Then the nut?<br /><br />On the subject of Silicone I have read to Use the 3M brand 5200 fast cure but also just plain old silicone what is your advise?<br /><br />Thanks for all the help.<br /><br />I am going to get the engine hoist in a few so I can get it out of the truck and on the back of the boat.<br /><br />PS anyone looking for a 1985 25 HP Mariner Remote in Excellent condition??

 

[Goodoleboy]

Re: Need Help Mounting 1986 50HP Johnson w T&T

Yep..Large flat washers on the inside you can us the zink plated washers if you cant find stainless steel ones. Stainless bolts tho. <br /><br />On the out side you will have to use smaller OD washers as you dont have much room their, Just flat washers. I like to use lock nuts the type with the nylon inserts in them rather than lock washers. But if you cant find that type nut then you can go with lock washers. I would use all stainless on the outside washers.<br /><br />But dont put a lock washer against your t/t unit itll chew the livin heck out of it.<br /><br />silicone brand is up to you. <br /><br />good luck!

 

[Goat67]

Re: Need Help Mounting 1986 50HP Johnson w T&T

Update<br />The motor is hanging on an engine hoist right now.<br /><br />When looking this over it looks to me as it would be better to put the bolts thru from the outside this way the motor mounts will be riding on the shoulders of the bolts what do you think?

 

[Goodoleboy]

Re: Need Help Mounting 1986 50HP Johnson w T&T

I dont think you can put em in from the outside. Hex is to large on the bolt head. but dont use smaller than 1/2 inch bolts.<br /><br />The hex nuts are smaller OD and will fit inside the chanells on the bottom sloted holes.<br /><br />More power to ya!

 

[Goat67]

Re: Need Help Mounting 1986 50HP Johnson w T&T

I do have enough room to go from outside using 1/2 inch bolts I have an inch to deal with the head or nut is smaller obiviously trying to find a SS washer this size is the trick.<br /><br />Regardless of which way it goes thru I understood you to use a washer on each side correct?<br /><br />SS on outside between the mount and the nut or head and <br /><br />Zinc if needed on inside<br /><br />Update it is on the back of the boat now I am centering it and getting ready to drill huntin for the second C Clamp.<br /><br />Thanks again for all the help gettin closer....<br /><br />Jerry

 

[Goat67]

Re: Need Help Mounting 1986 50HP Johnson w T&T

It's on!<br /><br />Thanks for all the help everyone!