61 starcraft holiday 18' repower vs new boat

[19611starcraft]

HI everyone I have a 1961 starcraft holiday 18' with a evinrude 100 from the 70s, iam in the process of replacing the transom and floor right now.I like the boat but I want to run a new 4 storke outboard like a mecury 115hp .I know the plate at the back says its rated for 115hp will the new transom will able to handle the new outboard or should I look at a new boat

 

[mr 88]

IF you do the transom correctly then you should be good to go. Keep in mind that the HP rating from the 50's to the early 80's have changed. They were rated at the crank and are now rated at the prop. So there is about a 10-15% difference. A newer 100 today would be equal to a 110-115 from that era. Actually surprised it would be rated at 115 . First 100 hp made by Merc was in 1962. Unless they were doubled up,then you could hit 115 no problem and based on the weight of two 55/60 hp engines I think one new 4 stroke would be lighter. I wouldn't hesitate if I loved the hull. There wasn't much deadrise in those hulls so there decent for flat water,trolling,drifting and anchoring but not so much for the rough stuff under power.

 

[19611starcraft]

Ok thanks I was not sure if a mercury 115hp would be heavier or lighter then the evinrude 100hp 1632cc that the boat has now and iam not sure if a 90hp would be under powered for the boat .I like the boat seems to be built strong and a new outboard motor is still atleast half the price of a new boat and I can always change the boats layout later .the transom is exterior ply wood glued and screwed with 3 or 4 coats of expoxy then painted with 3 -4 coats of paint I search the fourms on this site before I built it

 

[mr 88]

Stripped a 67 Holiday for my son , used for waterfowl hunting. Has a old 2 stroke 90 hp Merc Tower on it. The boat rips with 4 - 5 Hunters and all there gear,decoys,winter hunting clothing ,6 hp emergency kicker. He was dubious when I threw that ol Tower on it,now a believer and raves about the power and top end. Lack of deadrise allows it to achieve speed with that load. Anything over 75hp.in a newer rated engine will.move her along with no problem. The rule of thumb is to be at least within 65-75% of rated max hp

 

[19611starcraft]

Iam guessing I would need a long shaft outboard not a short right .I may also be piling a tube or wake board so I think I would want the extra hp I was just worried about ripping apart the transom it a new 4 storke was heavier

 

[Lightwin 3]

I'd be more concerned about weight vs. HP. Your old engine probably weighed 300#. A new 115 will weigh more.

Considering the old engine was "crank" rated, a new 90 would be a nice fit. It will weigh about what your old one did. Maybe a trifle more but considerably more noticeable HP.

The Four Strokers have the HP but it feels different. Not as much snap. The power comes on smoothly and builds.

 

[19611starcraft]

Ok see that's what I was not sure about the weight iam guessing a new mercury 90hp 4 storke would be close to hp of my old evinrude .

 

[mr 88]

You will need a short shaft. Measure the height of the transom and either check with dealer or report back here,

 

[Texasmark]

Ok thanks I was not sure if a mercury 115hp would be heavier or lighter then the evinrude 100hp 1632cc that the boat has now and iam not sure if a 90hp would be under powered for the boat .I like the boat seems to be built strong and a new outboard motor is still atleast half the price of a new boat and I can always change the boats layout later .the transom is exterior ply wood glued and screwed with 3 or 4 coats of expoxy then painted with 3 -4 coats of paint I search the fourms on this site before I built it

The 'rude of that day was a descendant of the famous first 50 hp V4, the "Fat Fifty". Got it's name obviously. Don't sweat the weight. If worried, increase the bracing between the transom and the sides of the hull with angle brackets. When I redid mine with a 110 I/O I just used ¾ 5 ply plywood, 2 layers to get the 1.5" thickness. Marine glued them together and soaked in a penetrating oil base stain (for the penetration, not necessarily for color but Mahogany looks nice, then Shellacked over for a final seal. Same with the floor. Preferred Shellack over poly as it too penetrated.

I think your engine is the perfect size for that boat. I loved mine and it big water just fine for me. I didn't run 35 in swells. Plenty of free board, plastic windshield and front deck shed water that came on over in big ones. Obviously a semi V with dead rise at the stern rides better than a flat hull in seas, but is less stable at rest.....not like a tri-hull, course the tri-hull had the problem with pounding in seas.....Cathedral hull pretty much solved both problems in fiberglass from other mfgrs. Being aluminum, the hull is light for it's water displacement so yes it is something like a cork (well sorta) on a fishing line......but not all that bad.

 

[ahicks]

FWIW, 4 stroke 90 Merc is pretty much the same engine as the 115 - same weight.

 

[Doh]

I grew up in my Uncle's 19' Holiday with the First Year 90 hp V4 Johnson (1963 I think). The motor was the size of a House!

Weight will not be any problem with today's Mid Range offerings.

As for the Boat, the 90HP, never had any problems pushing the boat, regardless of loads. He did repower the boat in the early 80's with a 80HP Merc. That motor was a Dog and struggled pushing the boat.

At the same time my Dad had a 1979 115 Johnson on a 18 SS, which would walk all over Uncle's Holiday. Later Dad repowered with a 1983 90HP Yamaha, which was everything the 115 Johnson was and lighter.

You would be safe and happy, with anything 90HP and over.

 

[19611starcraft]

According to mercury Web site the 115 and 90 weights are the same at 359lbs so may as well get the 115