1971 16-footer 110-HP OMC V4

Optimizing the performance of Boston Whaler boats
mtjarrett
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1971 16-footer 110-HP OMC V4

Postby mtjarrett » Tue Sep 24, 2019 5:00 pm

I have a 1971 16-footer which may be a NAUSET 16. It came with a 1986 Johnson 110. I feel like 110-HP is to much power and the engine too much weight for this boat. The boat is difficult to turn to port (I think).

boat - 500px.jpg
Fig. 1. A pre-smirk 16-footer with OMC V4.
boat - 500px.jpg (80.11 KiB) Viewed 5019 times

I'm not concerned about boat speed. I would like to someday pull my kid knee boarding, and maybe take the boat out to the [Gulf of Mexico]. But mostly I move from place to place in the very shallow Laguna Madre of South Texas to go fishing.

I'd love to hear your opinion.

Q1: is the 110-HP too big?

Q2: Should I consider getting another engine?

Q3: If I should get a new engine, what engine is recommended?

Thanks.

jimh
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Re: 1971 16

Postby jimh » Tue Sep 24, 2019 5:14 pm

The boat is not a NAUSET.

The boat was probably rated for 100-HP by Boston Whaler. The year of manufacture likely predates the Federal Boating Safety Act, so there may not be a required capacity plate on the hull.

Many 16-footers are powered with 70 to 90-HP ENGINES.

An Evinrude E-TEC 90 has been a popular choice.

A Yamaha F70B is another nice engine.

The OMC V4 you have now will run forever with proper care, routine maintenance, good oil, and clean fuel. And it is paid for.

When you see how much a new engine costs you may begin to like the one you have more.

ASIDE: the engine appears to be mounted on a set back bracket.

High steering force is often caused by poor engine trim.
See the owners manual about this topic. If no owner’s manual then read mine on-line:

http://continuouswave.com/whaler/reference/manual9-17/

mtjarrett
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Re: 1971 16

Postby mtjarrett » Tue Sep 24, 2019 9:20 pm

Thank for the reply Jim.

I have two more questions:

Q4: from the photo, does it seem that the boat is sitting properly or is it too weighted in the rear?

The engine has a setback. I am curious as to why you pointed that out.

Q5: Should I take it off?

biggiefl
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Re: 1971 16

Postby biggiefl » Wed Sep 25, 2019 11:30 am

Engine is not too heavy. Set back bracket offsets the weight some and makes reversing a bit more difficult. Setback(jackplate) adds speed if set up correctly and allows for running in more shallow water.Many people have overpowered their 16/17's with 115hp or more. What Jim said is true about steering. If engine is all the way trimmed in, steering is usually difficult to port as the torque of the right hand propeller is fighting you. Besides mediocre fuel mileage, no need to repower unless you want to. You want to trim up(or out) at cruise until the wake flattens out so to speak. At WOT you want to trim it until it blows out(slips) and then bump it down until it grabs. Lastly you don't want to porpoise(unless you like getting sick) so trim down to stop it if it does happen. Usually those hulls do not porpoise too much like a 13 does.

As far as model is concerned, you have a 16' custom.
On my 24th Whaler. Currently in the stable: 86 18' Outrage, 81 13' Sport(original owner), 87 11' Sport, 69 Squall. :roll:

jimh
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Re: 1971 16

Postby jimh » Wed Sep 25, 2019 1:38 pm

A4: Re the static trim as seen in Figure 1: the bow is probably higher than normal, probably due to the weight of the set back bracket added and to the increase in distance from the transom of the engine due to the bracket.

jimh
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Re: 1971 16

Postby jimh » Wed Sep 25, 2019 1:45 pm

A5: Re removing the set back bracket: I don’t have a strong opinion on this question. I suspect the bracket is making the bow very light.

Without seeing how it has been set up in person, to tell if the bracket is set up properly will be difficult. Usually a bracket like that is used to raise the engine so the engine gear case and propeller can run in shallower water and also to reduce drag (in the expectation of more speed). Whether either outcome is realized is hard to know without before-and-after test data.

Also, the complaint about hard steering could be an artifact of poor rigging of the steering caused by the bracket mounting.

Q6: What type is the steering on this boat?

jimh
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Re: 1971 16-footer 110-HP OMC V4

Postby jimh » Wed Sep 25, 2019 1:51 pm

Q7: Is there really a 110-HP decal on the engine cowling?

I don’t recall hearing of an OMC V4 with that horsepower rating.

biggiefl
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Re: 1971 16-footer 110-HP OMC V4

Postby biggiefl » Wed Sep 25, 2019 2:13 pm

They made the 110 for a couple of years in the 80's for whatever reason. Kinda like the 185hp. It is not a SPL version like the 88 or 112 and hence why I "assume" it has PTnT. Looks to be a 1985 but not a great pic.
On my 24th Whaler. Currently in the stable: 86 18' Outrage, 81 13' Sport(original owner), 87 11' Sport, 69 Squall. :roll:

mtjarrett
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Re: 1971 16-footer 110-HP OMC V4

Postby mtjarrett » Wed Sep 25, 2019 3:23 pm

A6: It is a cable steering system.
A7: It does say 110 on the cover. I was told when I bought it that it was a 1986. I don't have a title for it though. There does seem to be a 1986 110 in the NADA guides.

Regarding it being customized:
Originally the console looked like this one - https://www.powerboatlistings.com/view/54178

The interior hull structures look the same as the one above as well. I removed everything, re-glassed and gel coated the inside, painted the outside, and built the custom console, seat, and rear deck.

I also moved the fuel tank to the rear, which it sounds like along with everything else you guys have mentioned, may have been a mistake.

I appreciate all the help. I have watched a couple videos on Youtube regarding properly trimming the motor. I will try to test this out on my next voyage.

jimh
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Re: 1971 16-footer 110-HP OMC V4

Postby jimh » Thu Sep 26, 2019 8:03 am

Re mechanical cable steering: check to see if there is binding in the cable steering. To do this, temporarily disconnect the drag link to the engine tiller from the cable actuator. The steering effort at the helm should be very easy and have no binding. If not, there may be some bends in the cable that are too small radius.

stubaird
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Re: 1971 16-footer 110-HP OMC V4

Postby stubaird » Thu Sep 26, 2019 3:43 pm

In my whaler experience, raising the jack plate and/or how the motor is mounted on the jack plate, if possible, will help in many ways including reducing porpoising and making for easier steering.

Stu

biggiefl
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Re: 1971 16-footer 110-HP OMC V4

Postby biggiefl » Thu Sep 26, 2019 3:49 pm

It looks pretty high in the pic.
On my 24th Whaler. Currently in the stable: 86 18' Outrage, 81 13' Sport(original owner), 87 11' Sport, 69 Squall. :roll:

Don SSDD
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Re: 1971 16-footer 110-HP OMC V4

Postby Don SSDD » Sat Sep 28, 2019 8:41 am

Some cable steering systems/outboards have poor greasing systems and get rusty on the starboard side, the advice to check the cables with the tiller disconnected will uncover this.
With cable steering I adjust the trim until there is no prop pull on the wheel, you can remove your hands and the boat does not steer itself to starboard. And as advised, if you go too high, it will cavitate or porpoise just back it down a bit.
If you get a newer outboard, you may find it hard to get one much lighter than this old one, almost all of the new outboards are heavier than the old ones with the same hp.
1986 Outrage 18 with 2001 Honda 130 HP
Former Owner 1991 Guardian 19 with 1994 Evinrude V4 140HP
Former owner 1987 Montauk with 1998 Mercury 90HP
Nova Scotia

Acseatsri
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Re: 1971 16-footer 110-HP OMC V4

Postby Acseatsri » Sun Sep 29, 2019 7:20 pm

The hard steering in one direction could also be caused by the engine [steering] tab being improperly adjusted. If it's hard turning to [port], the [trailing edge of the steering] tab should be moved more to [port].

biggiefl
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Re: 1971 16-footer 110-HP OMC V4

Postby biggiefl » Mon Sep 30, 2019 2:33 pm

Many times the trim "tab" on a jackplate does not do as much due to elevated height. Steering is easy to check as the jackplate makes installing the cable a cinch.
On my 24th Whaler. Currently in the stable: 86 18' Outrage, 81 13' Sport(original owner), 87 11' Sport, 69 Squall. :roll:

mtjarrett
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Re: 1971 16-footer 110-HP OMC V4

Postby mtjarrett » Mon Sep 30, 2019 7:20 pm

I disconnected the [drag link to the engine tiller] and the steering is far from easy to turn either way. I removed the rod that extends to turn the engine and put some grease inside the housing. That didn't seem to make a difference.

Regarding the [technique for adjusting the outboard engine steering trim] tab: I have read a lot about adjusting them. [Lengthy descriptions using terms “left” and “right” have been deleted—jimh]

jimh
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Re: 1971 16-footer 110-HP OMC V4

Postby jimh » Tue Oct 01, 2019 11:11 am

You cannot use terms “left” and “right” to describe athwartship directions on a boat because they are ambiguous.

For clear advice on trim tab adjustment read

http://continuouswave.com/whaler/refere ... ml#trimTab

The method is explained in one sentence:

For example, if the boat pulls to starboard, move the trailing edge of the trim tab to starboard.

biggiefl
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Re: 1971 16-footer 110-HP OMC V4

Postby biggiefl » Tue Oct 01, 2019 11:28 am

Sounds like new cable time. I personally replace the helm and the cable if I am not sure when it was last changed. It is not that much more $.
On my 24th Whaler. Currently in the stable: 86 18' Outrage, 81 13' Sport(original owner), 87 11' Sport, 69 Squall. :roll:

jimh
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Re: 1971 16-footer 110-HP OMC V4

Postby jimh » Tue Oct 01, 2019 1:21 pm

The interior of the engine tilt tube may also be badly corroded. Replacement of the tilt tube can be a difficult chore.

mtjarrett
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Re: 1971 16-footer 110-HP OMC V4

Postby mtjarrett » Tue Oct 01, 2019 6:40 pm

if the boat pulls to starboard, move the trailing edge of the trim tab to starboard.


Thanks, that's what I needed to know.

Regarding new steering: Will pneumatic be worth the money and is it possible?

Regarding replacing the tilt tube: Can this be done without special tools?

mtjarrett
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Re: 1971 16-footer 110-HP OMC V4

Postby mtjarrett » Tue Oct 01, 2019 8:35 pm

I might have an opportunity to trade for a 1991 Yamaha 90hp. Who would be the winner in that?

jimh
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Re: 1971 16-footer 110-HP OMC V4

Postby jimh » Wed Oct 02, 2019 6:09 am

mtjarrett wrote:Regarding new steering: Will pneumatic be worth the money and is it possible?


I have never heard of an outboard engine steering system that used air pressure. Where do you find these devices?

mtjarrett
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Re: 1971 16-footer 110-HP OMC V4

Postby mtjarrett » Thu Oct 03, 2019 2:46 pm

sorry. I meant hydraulic.

biggiefl
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Re: 1971 16-footer 110-HP OMC V4

Postby biggiefl » Mon Oct 07, 2019 11:28 am

All depends on condition and desired performance. The 90hp Yamaha is known to be more like 80hp. You will lose quit a bit of speed and holeshot. You will gain a lot less weight, much more quiet, and much more fuel efficient. The Yamaha almost sounds like a 4stroke compared to the crossflow V4 OMC which sounds like a diesel truck.
On my 24th Whaler. Currently in the stable: 86 18' Outrage, 81 13' Sport(original owner), 87 11' Sport, 69 Squall. :roll: