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This boat originally had a 225 Evinrude Ocean Pro when purchased new. Engine died, and I found a Yamaha 225 Four stroke. Engine runs fine, not to fast, but in rough water I am having a problem with the bow easily going airborne and coming down hard. I think the four stroke is about 80-100 pounds heavier than the Evinrude 2 stroke.

two questions:

I have thought about getting a wing for the cavitation plate of the engine, but the consensus of what I see online is that these are a bad idea for anything over 80 HP. Any experience by forum members?

Second, the boat has trim tabs which are not operating. I believe they are 12" tabs. I am having them repaired/replaced next winter, but any thought about a bigger tab? Not sure the additional inches would work well because the flat part of the bottom hull on the outside is not much more than 12" before the hull angles toward the keel.

Thanks!

Nick

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Just checked with the Bennett manual, and I believe the tabs have a 9" span. The boat is in Maine, and I am npresently in Georgia, so I can't check until the next time I get up there.

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Others are more knowledgeable about the affects of trim tabs and use, even though I have them on my boat (1979 22' Revenge). However, I did change mine over from the separate hydraulic system that mounted on the interior of my transom to electric (you are welcome to the old cylinders if you want them). Very nice transition. My trim tab switch (mounted on the dash) has a readable idiot light set up so you know exactly the heights and settings. Once dialed in I go right to the setting I like. I keep one trim tab a setting lower than the other to compensate for bow height. Aside from my instruments, it is the only accessory that I hook up the motors ignition switch. When the key is in the off position the tabs automatically raise to the highest setting so as not to interfere with boat loading/unloading from a trailer.

I am not familiar with the back of your transom. However, the previous owner of the my boat installed the wider trim tabs and had to shim a small area of the transom because of a notch in the transom's configuration. I think I would prefer the 9" tabs that would not require the shim. It also gets pretty tight back there for installing transducers and such.

Garris

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Some would say you are going too fast for the conditions in a 21 foot boat.

When discussing tabs and foils, we have to ask: At what height is the engine mounted? Almost every dealer mounts outboard motors too low on Boston Whaler boats.

If the engine is all the way down, resting on the transom, it is too low. Proper height for a Boston Whaler is typically 2 or 3 holes up. This means:

Top set of bolt holes in engine bracket:

0 - Bolt here is "all the way down"
0
0 <--bolt here is "2 up"
0 <--bolt here is "3 up"
0

Raising the motor to the proper height will help the boat's attitude and engine trim efficiency.

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I am working on the same problem since I have the same hull wih a engine that is 170 lbs heavier than original.

All of the following will help keep your bow down; get your tabs fixed, get a stern lifting prop and raise your engine to the proper height (depends on prop).

The 9" tabs will be ok once you get them working.

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Educate me. What is a stern lifting prop?

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Mercury Revolution 4
Power Tech OFS4

Lift the stern and the bow is lowered. Works like trimming engine in or lowering your tabs.

Google will give you weeks of reading material.

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Nick, take things one step at a time so you don't spend money you don't have to. Get the tabs fixed first - I'm betting that once you figure out where to set them in various conditions, that will fix your problem entirely. We have a moderate-V hull boat (not a Whaler) on the Maine coast and I wouldn't be without the tabs.

The one exception is the motor mounting height - that can be fixed pretty much for free, so it's worth looking into.

Tim

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Thank you, everyone, for your help. I will certainly check out the mounting of the engine as soon as I get back up to Maine.

A couple of comments. The 1994 Outrage 21 required a 30' shaft. I understood (and here is where I sincerely appreciate everyone's knowledge) that the engine should be mounted at a height where the cavitation plate on the engine is even with the lowest point of the keel. If that is not the guiding factor, let me know. I had a certified Yamaha mechanic mount the engine.

Tmann, I will check on the prop after I get the tabs running. Thank you for that advice.

Phil T, it sounds from another post when someone was looking for a surveyor for a boat in Saco that you live in South Portland. That's where my boat is. (Aspasia Marina). I agree that the Driver (me) may be going to fast for conditions. My only defense to that is that I can't get the boat on plane at a slow enough speed, and keep it there to handle the conditions. You know the weather in Casco Bay and Saco Bay better than I. I do think, however, that the engine weight, coupled with the tab issue, is affecting how easily the bow goes up in the chop. Before this 4 stroke, we had a 200HP Yamaha 2 stroke that seemed to be the perfect weight (until it blew up). The tabs weren't much of an issue with that engine. Going around Cape Elizabeth to my favorite fishing spots seems rougher than before. I am from Saco, and have been going up every summer for decades. I feel like the boat is not overpowered, but that the back end is heavier than before.

Thank you all again.

Nick Papleacos

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That vintage Outrage 21 came with both the 25" (for single engine) and 30" (for twins) transoms, mine is a 25".

The Yamaha that replaced the 400 lb Mercury weights 570 lbs. These hulls perform much better with 400 lbs on the transom rather than 600 lbs. The Mercury was mounted 2 holes up and ran great, hardly ever used the trim tabs. The new Yamaha was mounted the same 2-holes up and I started running a Revolution 4 prop to get some stern lift to counter the added engine weight, but had bad problems with porpoising. Raised the engine all the way up and that helped a lot but I was not happy with the handling and porpoising. I was using less trim tab but still using more than I wanted just to keep from porpoising.

I just ran a PowerTech OFS4 prop and that made a world of difference, boat handles like it did with the feather weight Mercury and hardly any tendancy to porpoise. I did not need to use any trim tab and could trim the engine out 50% or so without porpoising. Minimum planning speed is 22-23 mph.

With the right prop you can mount the engine as high as it can go, neither the REV4 or the OFS4 ventilates in normal operation mounted all the way up. I would not mount higher than 1 or 2 holes up with a lot of other props and I would not mount lower than 1 hole up, this will put the ventilation plate an inch or two above the hull bottom. The higher the engine is mounted the less tendancy to porpoise (and a lot of other benefits).

And no, you are not over powered, they are rated for 300 hp, I've got 250 hp on mine.

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Nick -

For Boston Whalers, the recommended engine height is 1- 1 1/2" above the bottom of the hull, at a minimum.

You are right. I lived in So. Portland and spent 10 years on Casco Bay (March - November). My brother has rented an off season slip at Aspasia. I trailered my boat before moving to KY.

The sea conditions in Casco Bay are unique. In most cases it is rougher than the ocean. For this reason there is a big contingent of "fair weather" boaters.

I learned (the hard way) about proper boat/engine setup through trial and error and advice here. Dialing in a engine and hull takes a lot of work, trial, evaluate and retry.

With my last boat, I learned my motor (415 lbs) was too much for hull and was susceptible to shipping large amounts of water over the stern. Remounting the engine higher helped all around performance. Where many would slow down in 1-2' to soften the ride, my boat handled/rode better if I went faster.

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Just back from Maine, where I pulled the boat from the water for winterizing. Took a look at the engine and saw that it was mounted on the lowest of the four holes on the engine, which meant that it was as high as it could go on the transom. The cavitation plate is above the level of the keel. The top of the prop is just at the level of the keel. So this looks like the tabs need repair before I move the engine.

Is it possible that putting it lower in the case would make the engine trim control more effective? Just thinking about the geometry of the angle of the prop when it is lower in the water.

Thanks again, everybody!

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I would stick with TMann's advice since he has experience with the same model.

Not sure if fixing the tabs is better than changing the prop to an OFS.

Keep in mind, it is not unheard of to need a change of prop type with a repower.

Tmann, what do you say?

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Tabs will keep the bow down no matter what prop you are running. I don't like having to run a lot of tab in calm water since it is creating drag, I only like using them in snotty conditions when engine trim is not enough. (And my boat is not very sensitive to engine trim with the new heavy engine also.)

Recommendations are still the same. Since the enging is mounted all the way up I would fix the tabs if you just need more bow down when rough and calm water operation is satisfactory. But if you are loosing grip with the current prop (ventilating), I would get a different prop, REV4 or OFS4 will give you stern lift and excellent grip with the OFS4 being better at stern lift.

And don't even think of lowering the engine, it will only make matters worse.

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Here is a long overdue reply to everyone's advice. I did not put the boat in until this summer because of work. The rocker switches needed replacement. They make a world of difference. I am able to plane a little slower in the chop, and it makes for a much smoother ride. I still think the engine is probably a little heavy for the boat. However, that 4 stroke gets better mileage than the 2, and you all know how big the gas tanks were in the older boats. Thanks again, everyone.