140 Etec too much weight/power

[bayonnebandit]

I just posted about my bow eye but I have another question on the boat and figured it better to be a separate post. So, the boat is a 76 21 ft Mariner. It has a Max hp rating of 150. With Evinrude being discontinued, I am debating jumping on a Etec G2 140 given the incentives they have right now. That being said, the weight of the new engine is 390-415lbs depending on options. In doing research, I’ve surprisingly found out that 150hp engines back in the 70s were lighter than today’s (somewhere around the 300lb mark) and the hp was rated at the Powerhead not the prop. Given the added weight and the added thrust (these G2s are supposed to have an incredible amount of torque), do we think that it’s too much engine for the boat. I know it all depends on “how you run it” but I do like to get on the gas and I go out in the ocean off the NJ coast in some pretty rough seas from time to time. Id like the reliability and features of the new engine but I don’t want to install it and make a reef if you catch my drift. I’ve already installed a 1/8”x2” aluminum angle iron across the top of the transom for added strength, but I was thinking I may need to shore up the knee brace. Currently I can make it flex slightly at the bottom if I stand on the cavitation plate of the engine and jump up and down (not sure if that’s normal flexing or not).

Just for information my current 90 Etec weighs 320lbs

 

[Watermann]

The only 150 of the era that weighed only 300 Lbs was the Merc inline 6, all the others were V6's and weighed in closer to 400 lbs.

The power / torque difference of a prop rated 140 vs a flywheel rated 150 wouldn't make me worry at all especially on a 21'r, my 18' SS is rated at 140 and my 22' Islander is rated at 240.

With all new transom wood and fasteners in the stern there really shouldn't be any transom flexing that is noticeable. Another thing to strengthen the transom area is to replace some of the 1" screws along the bottom of the inner transom lip with machine screws and nylocs bolted all the way through like the V5's have. The V5's also have double knee braces. I've seen guys add AL braces from the ends of the deck supports to the transom.

Posting a pic of your set up always helps.

 

[GA_Boater]

The extra 100 or so pounds really shouldn't make much difference. If you move from the bow to the stern, how much lower does the stern sink? I'm guessing you weigh at least 100 pounds. You could also add some temporary ballast close to the splashwell and make a few test runs to see how the extra weight affects handling.

A 21 foot Mariner should be able to handle the extra weight. I would consider beefing up the transom with knee braces for the added 60 HP.

 

[bayonnebandit]

This is my setup. The transom is double 3/4 marine ply. Then I have an additional 3/4“ marine ply piece on the back for vibration. Everything is bolted through with 1/2” bolts in four additional spots beyond the four bolts that hold the engine to the transom. I also placed a 1/8”x2” aluminum angle across the top and used the same angle to make brackets for the lower mounting bolts of the engine so it distributes the load. With all that in mind the video is of me (190lbs) jumping on the cavitation plate. You can see right at the end of the video there is a little bit of wiggle right at the bottom of the motor mount. This would coincide with the knee brace. It’s a very small amount of movement but I didn’t know if that was “acceptable”. I was thinking of bracing the lower portion of the transom to the stringers but I didn’t know if that would put pressure on parts of the boat that aren’t supposed to have it. Any suggestions would be welcome
View attachment IMG_3819.mov

 

[N1265]

The only movement I am seeing is the movement of the camera, and therefore I personally would not worry about it.

 

[racerone]

Any flexing on an aluminum boat leads to cracking.----And is there a patch there already ??

 

[Branchh]

The all-new Evinrude E-TEC G2 140hp taps into three-cylinder two-stroke version will continue to power up high in the rev range, the 140hp outboard 140hp version that measured only 1.7 litres despite having an extra pot. bit of weight to push around, tipping the scales at 880kg dry and without the .