Boat Resurrection

[Jack Stasney]

Recently I came across a 16.5ft 1972 Larson Tri-Hull with a Johnson 100HP motor on it. The boat was always stored in doors and as such the fiberglass is in great shape. I recently had the motor compression tested and it came back with a reading of 80. So now I'm in a tough spot. I'm a fisherman so thats what I want to use it for. I think with some minor mods it could be a great fishing boat. Problem is I haven't ever had a boat like this so I don't know what to expect. Also with the compression as it is could I get away with using it for a few years as is? I had to get the trailer fixed so that cost me a few hundred, so I've got a darn nice trailer and an iffy boat. What would you do?

[Eric Wettschreck]

Compression is important, but are all they cylinders 80? If the cylinders are even at 80 I'd use it for a while and give myself time to decide what avenue to go down.

If it works for you this summer, and you like the boat and motor, maybe this winter you can purchase a rebuilt power head or the parts and rebuild it yourself.

[Valv]

80 is a little low for compression but if they are even it should be ok.

[Jack Stasney]

Thanks guys for the advice. I called the shop and they told me all cylinders are between 85-95. So hopefully this is a reasonable range and I should be able to just use it until I can make a decision on how much I really like the boat, tired as it may be.

[marine_man]

Well, you're close to within 10%, so it's a reasonable range, but it's certainly not ideal.

The motor will run, but expect difficult starting, perhaps rough idling and a general sense of lacking power.

Good luck!

marine_man

[Jack Stasney]

I talked to the mechanic this time and he told me that there were 3 cylinders between 90-95 and one at 83. This was not good. Probably would have run but... Also the engine being a 72 Johnson was a Hydro-Electric drive which controls the Tilt. I was told by a couple different mechanics that nobody works on these and if you had the engine rebuilt then the Hy-Elec failed I'd be all washed up. A rebuilt motor with no where to go. So at this point I've found a good deal on a early 80's 140hp from a reputable engine rebuilder, so hopefully no engine worries for a while. Also I'm replacing part of the floor under the seats where the previous owner put nails through to hold the seats in and its rotted. I'll post some pics, anybody interested in seeing the process?

[cribbageboy]

Glad you found a different motor. Compresion is key, and when you are getting a 10psi diffrence between cylinders you are need to start thinking rebuild, which can get costly in a hurry. I would have done what you did.

[marine_man]

Sounds like you made a good decision regarding the motor.

Sure, post your pics up while you go through the process. It never hurts!

marine_man

[Jack Stasney]

Okay I promise I'll get some pics posted just haven't had time to yet. On another note I am looking at getting a used bowmount trolling motor. Anybody have insight on wiring for both my 24v trolling motor and the rest of my 12v boat apppliances like a radio of the electric ignition on the motor?

[marine_man]

Is the boat pre-wired for a trolling motor? I'm guessing not...

If that's the case, find a location in the front of the boat if possible for your trolling motor batteries (2 for 24 volt), run some 6 or 8 gauge wire from the battery area to where you're mounting the trolling motor and wire it directly to the motor (especially if you're going to mount the trolling motor directly to the boat with no removable plate) and connect it to the motor. If you're going to mount the trolling motor with a removable plate, then install a trolling motor plug and wire you power cables to that.

On the battery side of things, connect one positive lead to one batterie's positive post, connect the negative lead to the other batteries (not the same battery as you connected the postitive to) negative post and make a jumper wire of 6 or 8 gauge wire that connects between one batteries positive post (the one that doesn't have anything connected to it) and to the other batteries negative post. Be sure to use an inline fuse or circuit breaker connected between the positive lead going to the motor and the positive battery post.

How many 12V accessories are you connecting? Is there a fuse panel under the console with open fuses?

marine_man

[Jack Stasney]

Thanks for the advice marine man. Yes there is a fuse panel, right now I'm not sure on whether there are any open spots. Lets just say there is...

And yes I am going to be completely rewiring the whole boat for the most part. As far as accessories go I'll have radio, motor(considering the starter as accessory), lights, bilge pump, livewell pump, fishfinder(s), possibly a marine radio, and of course then the 24v trolling motor. That's all I can think of for now.

[marine_man]

I would try and reuse the fuse panel if at all possible then. Run some heavier gauge (10 or 12 should be sufficient) to the fuse panel and run your accessories (excluding the trolling motor, motor and gauges- that gets it's own power off it's own cables) off the fuse panel.

Good luck!

marine_man

[harvey lee]

When I rewired my other boat that I sold last season, I wired the trolling motor to a seperate battery up front for that. My concern was with running only one battery that I may troll so long that when I went to start the motor, I would have a dead or close to dead battery.

If there is room and you wont mind the added expense, I would go with seperate batteries for the boat. I have 4 batteries in my new boat. I for the trolling motor, 1 for the accs and the big motr and one for the spotlight for night river fishing. I still carry a extra battery also.

[sparcebag]

Smart move Harvey,2 batteries minimum,I've ran 1 batt for troling motor so much my sonar did'nt have the power to function.I now have 3 but carry 2 in boat,new boat I'm working on will hold 4 batts.

[Jack Stasney]

Anybody ever used a Trollbridge to allow 24v and 12v operation off of two batteries and also charge them? I'm thinking of going this way it looks very convenient.

[marine_man]

I have not, however, it looks like a trollbridge will charge your trolling motor batteries from your main motor. These work best when you have a motor with a higher output alternator / rectifier than what your 100hp Motor has, unless you regularily make long runs (1/2 hour, etc) to give the batteries the best chance to charge.

However, with your motor I don't know that I'd spend the money on it due to the little charging you'll get off of it.

With respect to running 12V off the two batteries - that's not a problem - hook an accessory up to your trolling motor battery (1) just like you would with any other battery and you'll get your 12V.

Note that I would NOT connect a depth finder or radio to the trolling motor batteries as some trolling motors will interfere with a depth finder if they're connected to the same battery. Some of the digital trolling motors (Motor Guide & I think Minnkota's new Terrova is as well) don't affect it quite as bad. Also, on AM your reception will be terrible (not that it's a lot better when connected to another power source) if you connect it to the trolling motor batteries.

marine_man

[Jack Stasney]

Marine man just in case it makes a difference I've upgraded to a 140hp Johnson. Don't know if that will make a huge difference. I was wondering about charge time, but I also read on the trollbridge HSOforum you can wire this up to charge from your car battery while driving.

[Jack Stasney]

Boat pics. Finally I am getting around to doing this. So as you can see the old motor is still on the boat in these pics. Also notice the floor... it was bad. I started tearing it out and then took it to have the floor professionally replaced. Also after reading many of the posts on marine vinyl vs. carpet I decided to go with a gray marine vinyl cause I thought it would be great for maintenance and the guy doing my floor had some extra from a different boat he had just done. I know the floor looks pretty bad, but luckily the stringers were not damaged at all. Whew!!! I'll be getting the boat back sometime this week and I'll post pics of the progress.

[marine_man]

What did you get for a 140? Any idea on the year?

That'll help with the information.

And yes, it will charge off a vehicle battery if you attach the wires between the two ...

marine_man

[Jack Stasney]

It is a rebuilt '79 Johnson, sorry who needs specifics anyways

[marine_man]

That's not going to help your charging too much. I don't have the specs on a motor that old, but the output isn't going to recharge your trolling motor batteries too fast.

Good luck in your project!

marine_man

[Jack Stasney]

Any suggestions on where to mount my transducers? I'll have one finder located in the bow of the boat and the other at the console. I've seen people with them mounted on the outside of the boat on the transom which is fine, I don't have a clue as to where to mount the ducer for the bow of the boat. Also I've seen installations where with a fiberglass boat you clear away the fiberglass on the inside of the boat and then epoxy the ducer to the outer layer of the hull. Anybody know if this works well? My concern would be that having it mounted that way may cause some interference, but I really have no idea. Certainly this way would be a lot cleaner.

[marine_man]

Well, since you're talking about putting a trolling motor on I'd mount the bow transducer on the trolling motor.

For the rear one - you can either mount it on the rear of the transom or epoxy it to the hull. Epoxying it to the hull is a little more work, and definitely a permanent location, but is a little cleaner.

If done correctly interference isn't really an issue with a fiberglass boat.

marine_man

[Jack Stasney]

Yeah I think I'll try inside the hull for the rear, and I did finally decide to get the trolling motor that has Uni Sonar so that is not going to be an issue. Thanks again Marine Man

[marine_man]

Glad to help...

marine_man