100hp. Merc on 14ft. semi-v?

[haworth1967]

Recently purchased a super nice '64 Merc 1000E 100hp. short shaft motor. I seem to be getting a lot of negative opinions regarding the "overpowering" of my boat. Some have said my hull is "self-limiting" and extra hp. wont make it go faster. wondering what you guys think about it. The hull is a semi-v design, and was originally (back in 1954) rated for 49hp. It came off a 14ft boat with a similar hull configuration and did great. Let me know what you guys think.
Mike

[marshmat]

Hi Mike,
If your boat is rated for 49hp, a 50 is your limit. A 60 would start to make the boat pretty squirrely. Go to a 70, and you're now pretty tail heavy as well as overpowered, making the boat difficult to control on plane. Going to a 100 could very well rip the transom right off; even if it doesn't, the boat is now so unbalanced and so overpowered that it will be nearly impossible to control.
The maximum power an outboard-engine boat can handle is determined by several factors. The first is the total volume of the hull, and the way that volume is distributed. The width of the transom is also a factor, along with the control setup and location (tiller or wheel, and where in the boat the wheel is). Hull type and bottom shape is a factor; so is freeboard. In addition, there are structural considerations that can reduce (but never increase) the maximum allowable power.
If you really like this Merc, I'd suggest you look for a sporty, used hull that can safely take a 100hp motor. Going to double your hull's rating is quite likely to result in the loss of both boat and engine (but, hopefully, not crew).

[Frosty]

Sorry marshmat-But I bought a boat once,--- 18ft rated for 80HP It had a lovelly transom and a good slop well glassed in. I just didnt see why it was rated for 80 hp. I bought a 150Hp Merc Black max. ( yes it was a long time ago) It was a great bare footer. My mate bought it from me and fitted a 200hp!!!!!

With a 19 pitch it was a good pull for bare foot flying beach starts. With a 17 it would literally leep from the water and plane instantly.

You had to warn passengers before take off or they would end up with there face in the battery box. You had to be carefull with it. I would not ever pull the ski jump with it for instance.

World champion bare footers used to visit the club occasionally,--They thought it was the buisness. They prefered it to the Mastercraft. It was so much fun.

[marshmat]

Interesting story, Jack, I'd like to have seen that thing
There are some hull forms that can take massive amounts of power. Jack's appears to be one of them.
But on the vast majority of lightweight outboard boats- and Mike, your 14-footer (can you post a photo btw?) is likely a LOT smaller and lighter than Jack's 18, thus a lot more sensitive to both weight and thrust- overpowering is a dangerous gamble, and in the US it is illegal and will get you in deep sh*t with the police should things go wrong.

[Frosty]

You say it was rated to 50hp in 1954? So it must be wood then. Jeees its 52 years old. I am now concerned, I dont want to encourage you any more.

Please post a pic. Im trying to think of a 50 HP engine in 1954

[haworth1967]

Hi guys..
sorry it took so long to get back here. I am not completely discouraged yet. My boat is a semi-v dual cockpit aluminum runabout. (Lone Star Admiral). I have a catalogue pic of one with what appears to be an old merc. mark55 on the back. Dont have any pics on this computer of MY boat yet, but here's a couple of pics I have of "Admirals" so you can get an idea what I'm working with. I should say that the plan is to strengthen the transom with 3/8 aluminum plate, and build a small alum. cage off the transom plate that hugs the sides of the rear compartment and attaches in 4 places under the step plate area to better distribute the force. Also, im sure that I would have to weight the forward compartment and the bow to get it to plane out. Anyway, if all else fails, I will buy a bigger hull as Matt suggested and get a "tamer" motor for the Lone Star. She may be old, but shes super tight and built with really heavy guage aluminum. Definintely not an old tiller fishing boat. I will be posting some project pics soon.
Fraternally,
Mike Haworth

[stonebreaker]

Go for it. I can't see how adding the extra hp is going to somehow automatically make the boat wildly uncontrollable. It's not like you can't throttle back if the boat starts chine-walking or something.

A hotrod is a hotrod is a hotrod - whether it's a boat, a car, or a motorcycle. Just use the common sense you were born with and you'll be fine. http://www.bosshoss.net/products.asp

[haworth1967]

You guys crack me up!! Thanks for the words of encouragement! I tend to agree. If I can get it to float I feel pretty good about it. Doesnt have to be run W.F.O. (wide f**king open), but I dont want to die either, so I come here for some sage advice! Do you think I should scrap the old cable/pulley steering for something newer? I also plan to fabricate some gull wing type covers to enclose the rear compartment in case of unexpected power loss swamping situation.
Check out how clean this motor is!
Mike

[stonebreaker]

Dang, for something that's the same age as me, that motor's in great shape!

[haworth1967]

Yep, I know the feeling! I'm a bit more used up than it is! Ought to make the boys at the antique boat meets drool like my old dog!

[Frosty]

You gotta try it, or you will wonder for the rest of your life.

Jeees do you keep it in a coffin?

[haworth1967]

Youre right about that. And it would be great to be able to ski and tube behind the thing. I just won this great bilge ventilator on ebay for the rear compartment project! I long ago abandoned the idea that it would be a stock resto, but there are so few left, that as long as I keep the improvements professional and period-looking I dont feel too bad about making changes. It will definitely be a rat rod resto. I been sitting on her for 13 or so years, and have had a lot of time to project plan! Finding the correct windshield hardware was the toughest. I finally found a set at finewoodboats.com that cost a fortune. Now I have a full set for the front, and plan to use the two extra side posts for a small flat second windshield across the rear compartment. Also have some great old Chris Craft controls that I plan to mount in the center of the rear compartment.
The pics of the motor are in a shipping crate btw!!! lol yikes!
Mike

[RAWRF]

I have an 18 foot Lund Semi-V that is rated for a 55 hp and I put a 70 horse Merc on that someone gave to me. The little time that the engine was running right it was awesome, but I finally got tired of working on it, especially when I was floating down the river at 7mph away from home, so I in turn gave it away. Back to Yamaha's and Johnson's for me.

[haworth1967]

LOL I understand! I bought this motor from an outboard mechanic, so I'm hoping it will run right for a while anyway. I've heard that the old Mercs can be pretty cantankerous. Did you run that motor on a lift plate or just hang it on the transom?

[glassr]

Hi Hayworth,
My Father has your same boat. He removed the windshield and fordeck and made a small reinforced platform. We snook and tarpon fish all of the bridges in the Miami area when we get together.
He originally had a old Mercury 40hp on it.Then tried a 50hp and we finally stopped at a Mercury 70hp. We decided that that little hull really did not like doing more than 55mph, the chine walking was really scary and we actually spun it out twice when we tried an Evinrude 85hp that I had.
But the 70hp still makes it fly. It is a great boat, very rugged and simple to upkeep.
As far as the cable steering goes, a small Teleflex set up will work fine.
Or you could get crazy like I did and put a hydro set up on your boat.
It is a little more weight but it steers really smooth,and people always take a second glance at it.
But have fun and be real careful with the H.P.,these little hulls can hurt you real quick!
Happy New Year
glassr