24' Aqua Patio motor opinions

[Venomous Duck]

Just picked up a 1988 Godfrey Aqua Patio. It has a homemade 3/4 plywood bench in the rear and currently no other furniture. It has a 1970 70hp Johnson with aftermarket power trim on in. I had an identical 'Rude on my old 16' trihull without the power trim and wasn't to impressed with the performance of it. I acquired a 1985 115hp Mariner with power trim for it but was not able to get it on the water before discovering a rotted deck, so I am not sure on the performance of the Mariner (starts and runs fine on muffs). I plan on putting the two folding bench seats from the trihull in the front and maybe a small water slide on the front deck and adding a captains chair. It will also occasionally be pulling two teens on tubes, maybe skiing but unlikely. Passengers will usually be 2 adults and 1-3 kids, occasionally 4 adults and up to 6 kids.

For what we plan on doing with the boat will it be adequately powered with the 70hp, or would the 115hp be a better choice? The hull plate lists 115 as max horsepower and the transom is aluminum plate and the mounts are all good, so the extra stress of the bigger motor is not a worry. However, the boat already rides high in the front (judging by the water line on the pontoons) and I am not sure how it would ride with the added weight in the rear (about 125 extra pounds), or if the seats going in up front would compensate enough. I have the controls and the steering setup is the same so there wold be zero added cost putting the 115hp on, except maybe a new prop. Looking for some opinions, based on experience, what the better choice might be. Especially whether or not the performance gain would be worth the extra fuel consumption. Regardless of what we use on it, the other motor will be saved as a backup when the trihull goes to the dump.

 

[ahicks]

Just me (lazy by nature), but I'd try the 70hp to see if there's any way it will meet your needs. For cruising it should be fine. Hauling kids on tubes should be fine. Adults on tubes will want that 115....

Lawn furniture, especially the plastic Adirondack style, are cheap and work really well on boats like this. Not easily tipped over by wave action, and stack easily to get them out of your way. We generally carry 4.

 

[HotTommy]

70 HP is fine for tubing provided the rider just wants to get wet and is not looking for much excitement. To make it exciting for teens and adults, you'll want the added speed of the 115, especially in the turns.

 

[Venomous Duck]

Thanks guys. We are planning on taking it out this weekend to see how the 70 does. Not sure if we will do any towing though. The people we bought from said they just used lawn chairs. We are a little wary of that with the smaller kids, especially if I go with 115hp. Although they would free up a lot of cooler space

 

[1983 ercoa 21']

Coolers make for good seating also.
I started off with a 25 hp merc, 70rude,115 Johnny before converting to a tritoon .
I really liked the 70 s fuel economy. I liked the 115 speed .
I'm not much of a merc or mariner I prefer the simplicity of the evinrude and Johnson motors .
something to take into consideration is how far the transom is from the fence and deck. With the 70 tilted up measure you clearance if it comes within 6" of hitting anything I would measure the overall length of the 115 before mounting it and figuring out the 115 is alot taller and will hit the fence or deck.

 

[1983 ercoa 21']

When testing the 70 make sure it has the proper prop on it it should be a 13 pitch or a 11 . If you have a tach wot should be between 5000 and 6000

 

[BatDaddy1887]

If you are worried about the 115 weighing down the back too much while moving, your tilt trim will compensate and level it out as desired. Look at the motor mount on the 115 engine, see if it has a tilt/trim sensor (usually on left looking at the engine from rear). A white/brown wire comes from that sensor and goes into your wiring harness. Install a tilt/trim gauge, run the white/brown wire to it and find the sweet spot that keeps the boat level while moving. Sometimes, I trim the bow up to avert heavy waves, and tilt down to gain more speed.

 

[Venomous Duck]

Thanks guys. We took it out with 3 adults and 4 kids, with no towing, the 70 did ok with gps saying a top speed of 14mph. Felt a lot faster though and rode nice. Unfortunately on the way back to the ramp we lost forward gear, probably from hitting/dragging the prop over the years, local rivers are plagued with logs. Swapped the 115 over with no trouble, just working the bugs out of it now. Have no water from the telltale and steam from the vents above the cavitation plate. Looks like time for a new pump/impeller which I expected, just was hoping at least 1 trip on the river before tearing it open. Any way to test the temp alarm sending unit? I put 12v to the buzzer to make sure it is working. I would feel more comfortable if I knew for sure the sending unit was good too.

 

[Venomous Duck]

If you are worried about the 115 weighing down the back too much while moving, your tilt trim will compensate and level it out as desired. Look at the motor mount on the 115 engine, see if it has a tilt/trim sensor (usually on left looking at the engine from rear). A white/brown wire comes from that sensor and goes into your wiring harness. Install a tilt/trim gauge, run the white/brown wire to it and find the sweet spot that keeps the boat level while moving. Sometimes, I trim the bow up to avert heavy waves, and tilt down to gain more speed.

Thanks for the input BatDaddy. The 70 had an aftermarket trim and did a nice job, sure beats messing with the damn rod. The 115 doesn't look like it has a sensor. All it has coming out of the trim unit is green, blue, black to the solenoids, and red/wht, blu/wht, grn/wht to the controls in a harness separate from the main harness. At the controls they change to brn/wht, prp/wht, grn/wht with blu/wht for a trailer button, which I don't have on the controls. The control box 5 wire harness has a brn/wht coming out that the service manual says is for a trim gauge but I haven't chased it back through to see if it follows through to the motor harness.

 

[Venomous Duck]

One more quick question. As far as mounting the motor, is it better to have it mounted high, low, or in the mid range? The 115 Mariner has 6 sets of mounting holes the can change the elevation of the motor. I currently have it mounted as high as I could, due to mostly shallow rivers with sandbars and logs, in our area. Is it possible to add a trim alarm?