Outboard motor for my drift boat

I need some help here. I just bought a pristine 1964 Merc 9.8 for my drift boat. It is supposed to be a long shaft but when I got it home and mounted it on the transom it looks too short. It measurers 20" from top of transom to cavitation plate but the cavitation plate is even with the bottom of the transom. It looks like the prop will barely be in the water. Of course this is mounted on the trailer so I'm eyeballing it. The boat is in the process of restoring and I could notch the transom to lower the motor. It has a metal plate that mounts over the transom to accommodate the motor. any ideas?

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Permalink Reply by Rick Newman on July 24, 2013 at 7:17pm

It is my understanding that not all "long shafts" are the same length. The options that come to my mind are: 1. Exchange the motor for one with a longer shaft.

2. trim the boat so more weight is in stern of boat.

3. Cut down the transom.

I'm sure someone will offer some other ideas soon.

Good luck,

Rick N

Permalink Reply by Mark Heskett on July 24, 2013 at 7:30pm

Rick,

thanks for the reply. it's hard to tell with the boat on the trailer. I really would like to make this motor work but I think cutting the transom is probably a solution. I should probably post a couple of pics to clarify.

Mark

Permalink Reply by Mark Heskett on July 24, 2013 at 7:44pm

Permalink Reply by Rick Newman on July 24, 2013 at 9:24pm

I think you are going to have to not only lower your motor but change the angle at which the motor enters the water. I don't know if you have tried to wrangle a drift boat with a motor yet but in my experience it is a very busy operation as the shape of the drift boat hull isn't designed to be powered. It is a series of minor corrections every few seconds so the better you can align your motor perhaps the better the results. I am wondering if a bolt on outboard motor mount like those found for trolling motors on big power boats might not be a solution. You can drill a few holes and mount the unit at whatever level you need without changing the boat. I don't know if you can change the angle of these mounts in order to get your motor level. Some of these mounts are also setup so that you can raise or lower the motor which might be handy in some situations. I'm sure that there are other solutions, lets see what other folks suggest.

Rick N

Permalink Reply by tungsten on July 25, 2013 at 6:26am

That is a cool lookin outboard,

Permalink Reply by Mike Baker on July 25, 2013 at 1:26pm

Hey Mark,

20" is a long shaft, 15" is short and 24" (I think) is extra long or sailboat length. It looks to me like you will be fine. Once you get underway the rear of the boat will suck way down. Just be careful of cavitation when you first start out and you will be O.K. I also think that is a Bitchin' motor to put on a wood boat.

Permalink Reply by Bill Craig on July 25, 2013 at 4:18pm

The plans for my drifter suggest a Doel Fin if an outboard motor is mounted. They creat an extension of the hull, improve planing performance  and reduce cavitation.

Permalink Reply by Mark Heskett on July 25, 2013 at 7:04pm

Thanks for the response  guys. Bill I did get a doel fin with the motor so I think maybe the motor was intended for a drift boat by a previous owner. I have 20" from the power head to the cavitation plate and about 19" from the base of the motor mount to the cav plate. I really want to make this motor work since it is such a cool vintage motor that is in new condition. Starts up and runs like a champ has a new impeller and you could eat off the engine. I'm thinking I might cut a 2" slot in the transom to lower it that much but I will check to see if it's going to affect the steering if I go this route. Open to any input. Thanks

Permalink Reply by Phillip Westendorf on July 25, 2013 at 7:59pm

Mark,

Before you start wacking on the hull you "Must" know where the waterline is with the boat loaded and the motors weight included.  Then do as Rick suggested above pick up a trolling motor (kicker) mounting bracket that is used on larger boats for adding a kicker and secure it to the transom.  

It will afford all the adjustment you'll need to bring the cav. plate in the proper position.  

Scrap the Doel Fin thing, it's ugly and you won't need it.  They are used on power boats to provide lift to raise the hull on plane quicker.  Just imagine yourself flying down the Colorado "On Plane" in a Drift Boat.

You might need to consider adding  some gussets to stiffen the transom to the sides at the Sheer, Chine and/or Floor.  Remember it's a 9.8 H.P. Motor which will add a lot of stress on the rear of the DB which was designed for Rowing.

G'Luck,

Dorf

Permalink Reply by Chris Anderson on July 25, 2013 at 8:03pm

In my opinion, I purchased a long shaft motor for my drift boat because everyone I talked to said I needed a long shaft...once you are out on the water, and standing at the rear end of your boat, I had an extension handle, and stood in front of my rower seat, the long shaft seemed too long...I have no problem buying a shorter shaft in the future. This motor will work fine unless you have 900 pounds in the front of the boat...and you plan on going MACH 5  on a lake. I think this motor will work great - But I do recommend an extension for the motor arm - it will help - good find.

Permalink Reply by mitchell on July 26, 2013 at 8:47am

Imo your motor is going to be to big for your boat. Both in terms of weight and mussel. I've alway been told that db's max out at 8hp. Anything after that turns your db into a plow.  I've just gone to a 2hp long shaft. I've found that the 2hp will be plenty of power for what I plan on using it for. Crabbing, trolling soft bays and lakes. I do have a removable  6inch  transom piece that allows me to drop the motor down into. This promotes another problem. The tiller handle becomes somewhat limited in range. I can turn on a dime one way but not so the other. To turn on a dime to the starboard I need to raise my tiller handle up and off of the cutout to get my dimes turn. Soft turns are a breeze either way. Something to consider if your going to cut.

There are going to be BIG tradeoffs using a motor on a db. I've been using a electric for years and recharging batteries, lifting them and buying new ones for spent ones. This all led to the purchase of the 2hp. After one week of use I'm glad i got it but I do believe I'd rather have a true motor boat and leave the woody to DRIFTING. For some of us that's not going to happen. Make the best of what you have is what it is.

good luck with your conversion and be safe.

Permalink Reply by Mark Heskett on July 26, 2013 at 10:59am

Thanks for the input Mitchell. As far as the motor size most of the drift boats here (rogue river) are using anywhere from a 6 to 15 horse motor. On the river it is mainly used to motor back up to a drift. A 2 horse wont even move you upriver on the rogue. I do plan on using it on the lakes up here also. If I do a 2 inch cut out pocket that still leaves me with 2 inches clear to maneuver the tiller. But I think I will put the boat in the water and see where the motor sits before cutting down the transom. The guy I bought the boat from ran a outboard on it and I  think he was the one who added the steel plate on the transom for that purpose as I don't think the Rogue River Boat Shop did this to their boats, but I could be wrong. I've attached pics. 

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