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Good afternoon all, finally got my 1962 16' custom back in the water. I am running a 1989 120 hp evinrude and engine has just been completed at the shop and is running fantastic. My question is has anyone ever mounted an engine a bit higher than normal to compensate for a slightly wet hull and a heavy motor? I see all the discussions here about engine height and I'm thinking that with my hull slightly wet I might drill the template the equivilent of one hole higher than normal. Given that most whalers need the engine mounted at least two holes up and in some cases three holes this might give me play should I need it. Or does the water flowing off the bottom when at plane determine how much bite the prop will get. The only holes in the transom were through the bottom of the three holes on the top mount and the engine was all the way down. I believe this was done only to transport the motor by a previous owner who never put the boat in the water with this engine until I did this week.
The boat jumps on plane fine but does porpoise like crazy when running at any decent speed. I have a doel fin that came with the engine but it is not mounted. I figured tabs might be the way to go also.
I know the hull is wet but not sure of how much water it is holding. I have an 18 gallon fuel tank located below the center console and 1 battery located in the rear port corner
Love to hear your opinions on this .

Thanks,
Kevin

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No doel fins, no trim tabs on small Whalers....

Try putting the engine all the way up before drilling any new holes in the transom.
Have you read this article?
http://www.whalercentral.com/articles...icle_id=82

All see this read:
http://www.whalercentral.com/articles...cle_id=106

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The motor mounting height has everything to do with the spatial relationship between the gearcase of the motor and the bottom of the hull as well as the particular propeller being used. It has nothing to do directly with hull weight.

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Many on this site are in denial about the role of tabs on small whalers... I agree try raising your engine first and check ur prop, but if that does not solve your issue try tabs. A fin will not help...

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Our hull is heavy too and even with the engine all the way up, the A/V plate is still under water at speed. Saw this solution recently and thought it had some merit as there's no set back to change the static trim but does the trick in gaining extra engine height. Just another idea to consider... See the pic's in reply #13 in the thread below:

http://www.etecownersgroup.com/post?P...25-5363372

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Joe, I cannot put the engine any higher without drilling more holes which I am hoping to do only once. As I said the previous owner drilled the bottom of the three mounting holes with the engine all the way down instead of the top hole and I did not want to turn the transom into swiss cheese with three holes in 4". That was the reason behind my original question.
Tom, If I read your comment correctly, since the boat does get onto plane ok then the motor mounted all the way up in the correct holes would be the best I could do, even if the hull is wet as raising it anymore than that will affect the water flow coming off the hull and therefore the performance of the engine.

Last what is your opinion regarding the porpoising that I experienced? Is it more likely a motor height issue or does it have to do with the extra weight I am carrying in the back of the boat or a combination of both?

Thanks, Kevin

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That is my plan but for a different reason. When I raise my motor I will be blocking the splash well drain tube. I have 2 Aluminum plates 1/2 inch thick to go between the bracket and transom that I hope will add some strength as well as set the bracket back enough to allow for drainage.

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Hey Gam, my main objective is to eliminate as much of the porpoising as I can. Not concerned about top speed as the boat is actually way too fast due to the 120hp. I will probably try to find a way to govern it down so the kids can enjoy it without me or look to do a swap with someone for a smaller engine. Hopefully raising it to the top hole will help to flatten out the ride. I actually got my wife out yesterday (her suggestion) and we had a blast for a couple of hours but if I want her out consistently the bouncing has got to go.
Joe mentioned no tabs on a small whaler, does anyone know why? Have people had bad experiences with them or did they just not work well on the smaller hulls?
It seems like it has been a million years since I was in a 13 whaler, maybe Im just getting old, for sure the whaler is in better shape at 50 than I am.

Thanks

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Trim tabs would equal the Swiss Cheese you are talking about....

The easiest way is to fill the 2 lower holes in your transom and put them where they will allow you to raise your engine properly....
Filling 2 holes is a piece of cake....

See this article to view the holes I filled.
http://www.whalercentral.com/articles...icle_id=62

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Kevin -- Porpoising is primarily caused by one of two things, or both:

Center of gravity of the boat too far aft (too much weight in the stern).

Motor set too low in the water.

Porpoising can usually be alleviated by raising the motor (in conjunction with a better propeller) and moving weight forward or simply eliminating weight in the stern.

You motor should be at least two holes up on the transom and maybe three. Where is it now?

Which propeller are you using now?

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motor is currently mounted all the way down as this is the only holes that were drilled. I purposely mounted the fuel tank under the center console as I was aware of the weight concerns. The only other weight relocation I could make is the battery and that is just a group 24 and not deep cycle so if I need to do that then a smaller engine is in order. I do not know which prop is on there, it's aluminum not stainless so certainly not any of the props I see you guys discussing. Looks like my next step is to redrill the tramsom and raise the engine and see how that works. I'll keep you posted as to how I make out.
Thanks for the feedback.

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Kevin, There is no substitute for the collective wisdom from those who know our boats here at WC. My suspicion would be by raising the engine and getting the right prop you should have the problem of porpoising solved and I doubt the wet hull plays that much of a part. Weight aft might be some of the issue but start first with the higher mounting and prop and go from there before moving the battery.

Regarding the down tuning to keep it acceptable for the kids I suspect you might be able to play around with the throttle linkage a bit to keep the revs down. Do that after you get it all set up and performing right because you will want to match the prop to the specified engine RPMs at WOT. You can always play around with weight distribution by moving some temporary weight forward or aft to find the sweet spot, Kids work well for this! Trim tabs on a boat that already has PT&T seems redundant to me and adds a lot of extra and unnecessary holes right where you don't want them.

I don't know if you ever get flat water to run on but I am betting with your engine and the proper set up you could see 50 + MPH once it is set just right. That ought to put a tingle in your speed demons britches.

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Oh, if the motor is mounted all the way down, then there's your problem right there.

Look and see what the part number of the prop is. This is a critical piece of information. No other single piece of hardware will have as dramatic an effect on your boat's performance as the propeller.

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Thanks Gam, The only weight I really worry about is the oversize motor, I cant believe 1 size 24 battery is causing the problem.
I'll get that part number for you Tom. And hopefully get the boat to a spot I can pick off the engine and drill/patch the transom so we can see what she does sooner rather than later.
And if it doesn't work Ill be on here looking to swap a real sweet running 120 for something smaller.

Thanks