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Hello All,

Just acquired an old Montauk and wanted to see what motor height people set there engines at. I have a 1993 70hp johnson powering this vessel. I can tell from experience that I think the motor is set too LOW. The stern bracket is resting on top of the transom with no gap.

When at WOT, the motor is creating a rooster tail (wrong), when I trim up a bit I can get rid of this, but than the boat starts to porpoise badly, even on glassy water. I can hit about 31MPH as it sits right now, and the hull does have some moisture in it (can't tell how much, was drilling holes to fill with 2 part resin to fasten down the console and seating, prior owner DID NOT do this, so of course water could enter the hull).

I am a mechanic by trade and have already used a measuring stick to line up the anti-ventilation plate with the keel. At full trim down with negative tuck nothing is lined up. With trimming up and both items in line, the boat porpoises. Even with plenty of ballast in the front this is still happening, so I surmise the motor is too LOW.

Just wondering if anyone else has run into this and found a 'sweet spot,' to help save me the effort of getting out the motor crane and going through the whole trial and error process, not to mention drilling additional holes in the transom and re-tapping the motor to accommodate the height change.

Thanks.

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Unfortunately your motor is mounted in the standard/original dealer position.

Research, trial and testing have shown the engine and boat will perform much better mounted 2 holes up. Refer to this article for reference.

http://www.whalercentral.com/articles...cle_id=106

Once remounted, retest and report back. We can then discuss the appropriate prop.

I would expect the boat could reach 36-38 mph once tweeked.

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Thanks for the advice, I'll remount and give it a try. I wanted to save some time by hearing what others have seen work best with this boat/motor combination, and hopefully avoid having to drill unnecessary holes in the transom. Looks like I'll be drill a few new holes to get this right! The prop is turning 5400-5500 RPM, the right numbers for this motor, but is only a 15 pitch.

Hopefully with the adjustment I might be able to gain a pitch or two...that would certainly help top end speed and economy. Motor is a gas-guzzler by todays standards (2-4MPG).

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The Montauk was not made until 1973 so you must have an earlier model like a Nauset 16.

Let us know what model you actually have.
http://www.whalercentral.com/userphot...allery.php

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OK, looks like this is a Nauset/Eastport. Any updates on the recommendation for motor height? It is 16'7"...close enough to 17' for me!

Question - what is the difference between the hulls on the Nauset, Eastport, Sakonnet? From the pics, they all seem to look the same. I purchased this boat and none of the internals (seat/console) are period correct. I don't care about that, but I DO need to know how to optimize the motor performance along with the usual facts about the hull.

This is the first non-aluminum boat I've owned, so there is a learning curve here. Trying to do as much homework/research as possible.

Still a 'newb' to these forums, great resource for helpful info...thanks so much!

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The basic difference between the Nauset 16 and the Eastport 16 is that the Eastport has the Stern Seat.
The console and pilot seat are the same.

Hope this helps you determine which model you have.

Now assuming your motor is mounted all the way down, you most likely need to drill new holes in your transom to raise the motor up.
See this article and let us know how your motor is mounted.
http://www.whalercentral.com/articles...icle_id=82

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The hulls are identical.
The only difference between the models is the interior.

If the interior is not period correct or aftermarket, then you have a "Custom" model.
http://www.whalercentral.com/faq.php?...p?cat_id=5

How sure are you that it is a 1968 year model?
Many times the Title is not correct.
See this info to find out what year you have if you know the Stencil number.
http://www.whalercentral.com/articles...icle_id=61

1968 ................. 37601 thru 39750

We are getting close to knowing exactly what you have.
1968 Custom 16 ?

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There was no boat ID number. But, it does look just like the ones pictured from 1962-1973. I looked at all the models and my vessel is the same.

As a outboard mechanic (primarily Johnson/Evinrude 1945-2006), I call motors that have 5 different motors on them 'FRANKENMOTORS.'

This boat may fall under that category. The center console isn't period correct, and the seat is from a completely different manufacturer not original to the Whaler, but I'm happy with it.

Not looking to do a show room restoration, just a comfortable, presentable ride for regular boating.

Look forward to the feedback. Here are some pics, not done, still doing installations of stuff. Needs to be completely repainted and clear coated too. Last guy really cut a lot of corners.

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pic 2

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pic 3

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pic 4

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Following up. With the pics, is the recommendation to raise the motor by 2" based on experience and technical data? I was planning on 1", but dont want to compromise the transom by doing two adjustments if 1" isnt enough to stop the porpoising.

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I would drill the green holes as shown in the article and mount the motor 2 holes up.

Note I am saying holes, not inches.

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Thank you Joe and Phil. I did not see the 2nd article Joe had posted about changing motor height. Here are the pics of the motor as it is mounted currently. What has me itching my head is that it is already at the #2 hole for the top bolts. The bottom ones are blind holes with the stern bracket tapped.

Is it possible the top bolt holes were moved at some point during this boat's life, and are set lower than originally tapped? The hull does appear to have had work done to it in the past. I'm guessing the transom may have been worked on too?

Using the articles as reference, I really only have a single hole adjustment of height on the top bolts; the bottom bolts, I haven't put a measuring tape yet, but I don't think they will reach the bottom 'slide' pattern bolt orifices of the stern bracket.

Has anyone had one of these 70hp OMC's mounted on one of their Newport boats similar to mine? Best placement recommendations?

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pic 2

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From what I see you could raise the motor 1 more hole up, but that would mean you would still have to drill
new lower holes as the "stud" mounts will no longer work. I angled slightly upward [ drilling from outside of stern] for my bottom bolts to enter the splash well high enough to accommodate a nut and washer.

I think Phil is right to drill the green holes. It will allow whatever height or motor you use. I have a 1964 and a 1966 with Yamaha on them. I spent a long time reading about raising the motor and thinking what a lot of trouble it would be. I did it on the 1964 and realized it was a lot easier than I thought. I did the 1966 the following winter. Very happy with the results.

I did both alone, used a Bobcat and rope with the second one. If you have an engine hoist it will be easy.

Just for reference, the 1966 [which I can measure] sits 1 5/8" inch above the transom.

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Well, comparing the length of the lower unit for a yamaha may be different than an OMC. Even comparing length for different HP OMC's reveals different drops!

Your 1 5/8" rise is helpful though. I measured the rise by raising the motor "2 holes," equates to 1.5," so that may be a coincidence but seems like it would help.

Probably raise the motor up in the next week so I can retest. Any recommendations for simple ways to fill in those old holes?

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It appears whoever drilled the upper holes did not use the BIA standard.
http://www.whalercentral.com/articles...icle_id=82

There is a standard pattern for drilling motor holes that all manufactures follow these days.
I suggest you look at the drawing again and you will see that the upper holes are drilled 1 7/8" from the top of the transom.
Yours appear to be around 3 1/2 inches down from the top. Not even close to standard.

There is NO difference between Yamaha, OMC, Honda, etc. They all use the Standard BIA mounting pattern.
Yes, the holes on the motor brackets are spaced 3/4" apart. Thus raising the motor 2 holes results in 1 1/2 inch raise.
All motors on a 16/17/ classic hull should be mounted 2 holes up. Some motors should even be mounted 3 holes up with the right prop.

You will need to drill the upper "Black" holes and the lower "Green" holes so you can mount your motor using a modified BIA standard.
The lower holes being modified in location.
The upper holes following the standard.

Use 1/2" diameter plywood plugs from 3/4" or 1" thick plywood and epoxy to fill the holes.
See this article we have in our Reference section.
http://www.whalercentral.com/articles...icle_id=62

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To fill old holes it is probably easier to raise the bow than the stern. So, raise the bow as much as possible [the more the better].
Tape a piece of plastic trash bag, saran wrap ect. to outside of transom and whatever you want to protect splash well. Put an epoxy resin that has been mixed in a suitable container to squeeze it accurately in the splash well side of the hole. I use old saline bottles with the tip cut a little bigger. Fill the whole thing. Since you have not made the hull verticle, you will need to finish the splash well side with some thickened resin, or some other epoxy putty.

When you are drilling new holes it will give you a good read on any moisture in the plywood of the transom, if any.

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Thanks for confirming my suspicions Joe about the top drilled holes. Again, last guy really cut a lot of corners on this boat (as in, every aspect of it I'm finding). I'll make the adjustment as per everyone's recommendations.

I agree that the BIA standard for mounting holes are the same across brands. My point was that the lower unit for different motors isn't the same drop from stern bracket to ventilation plate, even within the same brand. For instance, a 1993 40/48/50hp OMC has about 22", whereas this 1993 60/65/70hp OMC has less drop.

The stern bracket pattern is the same, but the lower unit/exhaust housing isn't. So comparing the mounting height of the other guys yamaha to this OMC, it may randomly line up, but isn't necessarily right for the installation. That's why I was asking at the beginning specifically, have folks found a sweet spot for the 70hp OMC motors.

All good information though, thanks again for your help.


(please follow guideline #1 at the top of this page and use the full 4 digit year for everything)

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Basically immaterial for shaft length.
We can't measure that accurately.
They tell us 20" Long Shaft, 25" Xtra Long Shaft, etc.

We go by tested and proven heights on mounting.
1 hole up, two holes up, etc.
Regardless of brand, year, etc...

Don't complicate this more then it needs to be.
KISS......... Keep It Simple Simon

Drill the upper Black and lower Green holes and be done with it.
Done.
Now you don't have to think about it anymore.

Congratulations.

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I agree, there's what happens in the books, then there's what happens in real life. True knowledge is a combination of the two.

My understanding of motor height installation is that the anti-ventillation plate needs to be pretty close to lining up/parallel with the bottom center of the vessel. At least this is how things typically work with aluminum boat applications (the majority of my experience).

Is this still the general rule of thumb with these 16/17' whalers?

On a side note, as I've been drilling holes and filling with resin (for various hardware installation), I've noticed the rear of the vessel has water in it/damp. Mid hull to the front is dry. Does the rear end of these boats generally get damp as the years go on?

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Again, you are trying to complicate things from the past.

KISS.
There are over 500 years of accumulated information that tells us where to mount the motor.
C'mon, there are only 4 holes to mount the motor in.
Mount it 2 holes up and forget about it.

Drill the proper holes as recommended and get on with your life and your enjoy your Whaler.

Again, for me....
End of story.

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Sorry, I have to disagree in terms of trying to complicate things by asking questions. I'm trying to understand what the principles behind properly setting up a motor on one of these vessels are, if they are different than other vessels I've worked on/with. I've been a teacher for 20 years, education is what prevents further issues moving forward and helps people make decisions on their own.

Maybe some of that 'over 500 years of accumulated information' can explain the actual theory/principles on this, so that folks coming onto this website/forum can learn to think on their own, rather than depending on you or other regular posters.

So what happens when you aren't available anymore? What do people do then?

I appreciate your help!

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The old method of aligning the anti-cav. plate with the hull bottom is not true anymore. At least on these hulls with stainless props.
I am repeating this stuff from others with way more experience and from my personal experience.

Different subject, but after running alum props for 20 years, I switched to stainless because it came with the motor.
I am amazed that anyone uses alum. anymore except on a kicker.

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There are a lot of opinions on prop material type. The majority of mechanics I have as colleagues tend to frown on them from the standpoint that the prop will withstand a hit, but even with slip hubs (or drive/shear pins), it ends up putting more stress on the gearbox and generally damaging the gearbox moreso than an aluminum which would just bend/break.

YES, SS props lend themselves to a little bit more performance, but for an extra 1-2 MPH, not sure if it's worth spending all that extra money not just for the prop, but to fix your gearcase if badly damaged.

Dealerships will encourage customers to buy SS because the profit margin is much bigger both with the prop sale and the ensuing repairs after a collision. I've yet to meet a dealership, even Mom and Pops business, that won't try to squeeze more money out of customers this way.

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I have some experience mounting OMC engines on a "blue" Whaler 16'-7" hull, and it should be pointed out that these earlier boats had a shallower depth interior splashwell dimension. That is why the standard 8" vertical bolt spacing of the BIA bolt pattern does not work for the bottom bolts, and probably the reason why OMC invented the blind hole mounting system for the bottom bolts. It may have seemed like a good idea for the times, and for the kind of mostly aluminum props they had at the time, but for modern times it is a problem.

The information you have been given here is good - the engine has to be removed from the boat that those old holes filled. I have pruchased two used Whalers with OMC engines, and on both the engines were all the way down, blind hole mounted like yours (curse, curse), requiring removal and complete re-filling of the old transom bolt holes. I switched to Mercury power, but the same BIA bolt pattern applies.

The information you have been given relating to the bolt hole drawing on this site, and to use the "green" bottom holes is correct, and the simplest solution. This allows the bottom bolts to come into the splashwell, and receive the necessary washera and nuts. The bottom bolts should ALWAYS have the nut on the inside - the top bolts have the nut on the outside. This solution will automatically raise the engine 1-1/2", and is the maximum recommended for a lower HP engine like you have.
For best holding, a stainless prop may be required at this height, although a good design aluminum such as the mercury BLACK MAX or SPITFIRE 4 blade may also work. As a
Merc owner I admit I may be prejudiced, but I believe the Mercury/Quicksilver aluminum props are the best on the market and hold the best. They perform remarkably well for $100 they cost. I am not sure, however, they fit the gearcase bullet of the 70's. Check around first.

If you are worried about such a high mounting for a lower HP engine lilke a 70, you may also try the following. Measure your interior transom carefully, and see if you can use the "Yellow" bottom holes.
To do this, you probably have to raise the top holes a little higher than the standard 1-7/8", more like 1-3/8" or 1-1/2" If the transom is in good shape, you can do this, especially if you install the "transom stiffener bar" across the top bolts, about $20. I did this on my Outrage 19 - see photo

http://smg.photobucket.com/user/lgolt...4039058116

If the dimensions will work for you, this will result in an engine "raise" of more like 1" or 1-1/8", and will definitely allow use of an aluminum prop without slippage.

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I told you there were folks on here with more direct knowledge than me. I am happy to see that he also agrees
with what you have been advised to do. X#%* except for the dang aluminum prop stuff.
Just kidding!

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All good info (from everyone), thank you.

Appreciate the 'tip of the cap' to OMC, but one thing that I've learned is every company makes good motors and bad motors. And last time I checked, Mercury is still in business, OMC went the way of the doe-doe. There are 'those guys' out there who will say brands other than what they like stink, I'm not one of them. I kind of think of those folks as boat/motor racists! (smile)

I think Merc, Yamaha, etc all have good products, but you'll also find experienced mechanics and service techs from those companies who can tell you which generations/models of their product weren't that good. I can tell you a few for OMC too. Get talking with some of the top techs/service reps from the companies bass boat lines, you'll hear some great stories from all of them on which motors are turds and which things the engineers insisted on incorporating, even those the service techs told them before they went to production they wouldn't work!

I've heard good things about the quicksilver line of props too, so I'll look into that. Good info on the mounting bolts. The last owner really cut corners on this boat, so I was planning on putting some thick SS or aluminum plating across the inside of the transom for both the top and bottom bolts once everything is re-situated again.

What is the deal with SS props and whalers I'm picking up as a vibe in this thread? Diameter and pitch is the same regardless of materials. What is the difference?

Again - I know I'm a 'newbie' to these forums, but I deal with other mechanic related technical forums where I usually deal with retired mechanics or service reps from the actual manufacturing plants...so when I ask questions it's to understand the technical side too...not just the application.

Thanks.

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The principle of raised outboard motor operating height to e.g., "two holes up" on your Boston Whaler 16 custom hull is to improve overall performance. This means you will have less draft, reduced drag, improved time to plane, reduced steering torque and effort, and overall improved speed and fuel economy.

There may be other issues with your hull that could be causing poor performance, i.e., porpoising. I noticed in your posted photographs that the below the water brass drain tube on the exterior of the hull is failed. There is no lip shown in photograph. You may have seepage of water into your transom core, and, as a result, you are running "transom heavy." Have you weighed your boat? The bare hull factory weight of a 16 was at 500 lbs.