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Author Topic:   4-stroke repower: 17' Super Sport
PMUCCIOLO posted 05-20-2003 10:15 AM ET (US)   Profile for PMUCCIOLO  

A colleague of mine wants to repower his 17' Super Sport. He uses the boat primarily for cruising, not watersports. Related information is scattered throughout various posts, and I wanted to centralize it for a comprehensive review. Input from those who have (re)powered their 16/17 hulls with four-stroke power (including prop size and performance data) would be greatly appreciated. The brand of engine (Mercury, Yamaha, Suzuki, Honda, etc.) is immaterial, as the boat is going to be completely re-rigged. A stainless steel propeller is preferred.


JBCornwell posted 05-20-2003 11:36 AM ET (US)     Profile for JBCornwell  Send Email to JBCornwell     
Hi, Paul.

At the risk of being redundant:

I repowered my 1980 Montauk in 2000 with a Suzuki DF70 on a 4" setback plate (to avoid using lag bolts), SE Sport 300 hydrofoil and 18" SS prop.

I am very happy with the result. Though I am a fisherman and cruiser rather than a speed freak my boat will outrun most 70 2 strokes and keep up with many 90s. WOT is 39mph at 5800rpm.

I am particularly pleased with the instant, no hassle-no smoke starts, very smooth and quiet operation and the low fuel usage.

I have persuaded many of our colleagues to use the same engine (some in Johnson or Evinrude colors) and believe them to be equally pleased.

Red sky at night. . .

PMUCCIOLO posted 05-20-2003 03:33 PM ET (US)     Profile for PMUCCIOLO    

I appreciate your taking the time to provide a detailed account of your experience. I realize that redundancy will be a product of the nature of my inquiry on my friend's behalf, but any and all input is greatly appreciated.


PMUCCIOLO posted 05-21-2003 01:34 PM ET (US)     Profile for PMUCCIOLO    
Who has performance data & experience with the 50 or 60HP four stroke engines (Mercury or Yamaha)? I can't seem to locate the detailed data that I know is posted here.
Bigshot posted 05-21-2003 03:07 PM ET (US)     Profile for Bigshot  Send Email to Bigshot     
Same setup as JB, same tow vehcle, and same results, love it.
Dick posted 05-21-2003 08:55 PM ET (US)     Profile for Dick  Send Email to Dick     

1999 Montauk
50 HP Merc 4 stroke
4 blade Trophy Sport ss prop
Normal running is at about 1700# gross
Engine is mounted 2 holes up

Tops out at 33 mph (GPS) @ 5800 rpm and on step very quickly.


PMUCCIOLO posted 05-21-2003 09:33 PM ET (US)     Profile for PMUCCIOLO    
Thank you for the above information!


dogfish2 posted 05-21-2003 11:05 PM ET (US)     Profile for dogfish2  Send Email to dogfish2     
I recently repowered my Montauk with a 115 Merc, 4 stroke, EFI. The motor runs very smooth and throttle response is immediate, and suits my personal usage needs. If your friend is going to use his boat for cruising, then, I would follow the lead of others on this post and go with the 70 Suzuki. By the way, which set-back plate did you guys use, as I am looking to enhance performance. Thanks.
Royce posted 05-22-2003 12:11 AM ET (US)     Profile for Royce  Send Email to Royce     
JB- could you be more explicit about the prop you used. Three blade or four blade? What diameter and pitch? What brand? What kind of setback plate and where did you get it? Thank you.


JBCornwell posted 05-22-2003 09:15 AM ET (US)     Profile for JBCornwell  Send Email to JBCornwell     
Hi, Royce.

The prop was supplied by my Suzuki dealer. It is a 14x18, three blade SS. Most people end up with a 14x17 3 blade prop on this setup. Maybe the setback makes a difference, maybe they risk over-revving on occasion.

The dealer also acquired the setback plate for a ridiculously low price, I think it was about $70, but I don't know where he got it.

If you like, I can E you pics of the installation.

Red sky at night. . .

dogfish2 posted 05-22-2003 01:32 PM ET (US)     Profile for dogfish2  Send Email to dogfish2     
JB, would you please also email me a picture of your jackplate installation. Thanks for your assistance and courtesy.
PMUCCIOLO posted 05-26-2003 09:31 PM ET (US)     Profile for PMUCCIOLO    
He's down to either the 70HP Suzuki 4-stroke EFI or the Mercury 60HP 4-stroke EFI. Is the jack plate necessary?
JBCornwell posted 05-26-2003 10:49 PM ET (US)     Profile for JBCornwell  Send Email to JBCornwell     
Unless he wants to use lagbolts into the transom and to fill unused holes a setback or jackplate is necessary, Paul.

If he wants to know what it looks like I can E you a picture of my installation. It is much neater than I expected, but it still doesn't look like original.

Red sky at night. . .

Sal DiMercurio posted 05-27-2003 12:33 AM ET (US)     Profile for Sal DiMercurio  Send Email to Sal DiMercurio     
JB, question.
Why a 14 diameter on a 70 hp on a Montauk ?
I'm running a 14.25 dia on a 20 Outrage with a 200 hp & feel I could drop down to a 13.50 very easy.
14 dia on a 70 hp seems .....a bit much when it's really not needed.
That boat would perform better [higher speed ] with a 12.75 x 21 with plenty of hole shot boost.
My thinking is, use less dia & more pitch to control the rpms & gain much more speed, but not at the risk of having a poor hole shot.
PMUCCIOLO posted 05-27-2003 01:00 AM ET (US)     Profile for PMUCCIOLO    

Photos, please!


JBCornwell posted 05-27-2003 09:54 AM ET (US)     Profile for JBCornwell  Send Email to JBCornwell     
You have mail, Paul.

Red sky at night. . .

PMUCCIOLO posted 05-27-2003 11:10 AM ET (US)     Profile for PMUCCIOLO    
Thank you!
elaelap posted 05-27-2003 03:21 PM ET (US)     Profile for elaelap  Send Email to elaelap     
'71 Katama 16/17; 50 hp Yamaha 4 stroke High Thrust (like a Bigfoot); 13" pitch aluminum prop; ablative bottom paint; super quick out of the hole; 30.5 mph GPS WOT at 5900 rpm with 2 people and 17 gallons of gas onboard; 1.25 gallons of gas per hour cruising (3000-4000 rpm); can't measure gas consumption trolling; silent and starts first time always. I repowered in March, just put hour number 82 on motor...I am very pleased with this set-up.


jstachowiak posted 06-01-2003 10:42 AM ET (US)     Profile for jstachowiak  Send Email to jstachowiak     
I mounted a 70HP Evinrude/suzuki 4 stroke on my 1979 Newport and did not use lag bolts and mounted directly to the transom, without the jackplate.


PMUCCIOLO posted 06-01-2003 12:52 PM ET (US)     Profile for PMUCCIOLO    

You are quite a craftsman! The photos are superb!

PMUCCIOLO posted 06-12-2003 06:58 PM ET (US)     Profile for PMUCCIOLO    

The boat will be ready for power soon. The wood is nearly refinished, and some repairs had to be made to the hull.

You now have two choices from which to pick:

(1) Mercury 60HP 4-stroke EFI
(2) Suzuki 70HP 4-stroke EFI

Which would you select? Why? Please keep in mind that he wants the engine bolted directly to the transom (i.e., without a jackplate).


lhg posted 06-12-2003 07:49 PM ET (US)     Profile for lhg    
Paul - If you could talk him into the Mercury, you could then give us a first hand comparison report on the differences, if any, between the carbed Yamaha 60, and EFI Mercury 60. Since both are on the same Mercury designed and manufactured engine, this would be interesting to hear.
Bigshot posted 06-13-2003 10:45 AM ET (US)     Profile for Bigshot  Send Email to Bigshot     
True Larry but this is a 17' not a 15'.

Being a 17 i would prefer the 70 but the 60 would be OK.

lhg posted 06-13-2003 03:25 PM ET (US)     Profile for lhg    
Nick - according to Clark Robert's extensive experience with both boats, he claims the 15 and 17 run the same with same engine. I think there is info in the Reference section.
JohnJ80 posted 06-13-2003 04:25 PM ET (US)     Profile for JohnJ80  Send Email to JohnJ80     
My boat is a 15', but I think much of the experience is relevant.

I recently repowered my Dauntless 15 with a 75HP Evinrude FICHT DFI. I'm still tuning her up, but I think it is an excellent combination. Remaining task is to pick the motor up another hole and then fiddle with props.

Here is the link to that thread One note - I think the speeds are about 5-10% high but still pretty good for a D15 with a 75HP!

A lot of people thought that this would be too heavy (it isn't) and that it wouldn't perform well (it does). The old motor was a 70HP Johson 2 stroke with a Stingray fin. The new one is about 80 lbs heavier at 325lbs. The new one behaves pretty much the same but hole shot is faster, its is far quieter and it is faster at WOT. We have to traverse a fair number of no wake zone channels and the DFI motor does that so much better than the 2 stroke (less smoke, runs better at low idle, much quieter).

I would recommend the Grand Island Marine Turbo Lift fin (321-452-8126). Whaler recommended it to me and I am so pleased with what it did for me that I would recommend this as well. Other than improving the ride a ton, it also quieted down the engine noise/exhaust noise. With the plate on it is substantially quieter than the 2 stroke Johnson was by a long shot. Its also much quieter than the boat was without the fin on the same motor. I'm so pleased with the GI Fin, I would add one just for the noise reduction alone. Great product.

Vertical position of the motor - You are going to need to experiment with this and it is almost a guarantee that the dealer will mount your motor too low. Check where it is on the old motor and make sure that you can replicate that if you like the ride.

2 stroke vs 4 stroke weight - The 4 stroke will be heavier - of that there is no doubt. You may need to fiddle with the motor mounting, prop, fins etc.. to get this right. It will change the dynamics of your boat but you should be able to trim it out. I would have a chat with Chuck B at whaler tech support to see if there are any issues with particular motors on particular boats. For example, on the D15, there was service alert on putting on a 75HP honda. That motor is one of the heaviest and it carries its weight aft on the motor frame. The combination of the Honda and the D15 was a noted problem. There may be a similar list for your boat (motor/boat combinations).

Repowering is not simple. I spent a lot of time on this and had to pour over a lot of data from the dealers, Whaler, Grand Island Marine, and this forum. I suspect I got to be a pain in the hinder to Chuck Bennett at Whaler ( and to others in that list). To Chuck's credit he calmly put up with all my questions. He was a great help. I would strongly encourage you to discuss this project with him.

Hope that helps.


Perry posted 06-13-2003 09:43 PM ET (US)     Profile for Perry  Send Email to Perry     
You still believe your 75 ficht weighs 325 lbs? Try put it on a scale. A friend of mine has 2 of them on his outrage 18. He was concerned about the weight issue so put one on a scale. It weighed 366 lbs with oil in the sump.
Bigshot posted 06-16-2003 10:46 AM ET (US)     Profile for Bigshot  Send Email to Bigshot     
Catalog says 362 or 368 for the 75-115 Ficht.
Bigshot posted 06-16-2003 10:47 AM ET (US)     Profile for Bigshot  Send Email to Bigshot     
Ps....Larry the 15 with a 70 will run over 45(mine did 48+). 17's will run maybe 38-40 with a 70.
PMUCCIOLO posted 09-28-2003 08:23 PM ET (US)     Profile for PMUCCIOLO    

The wood and fitting have been refinished, but it looks as if the hull has problems...major ones. Most of the deck is wavy and the hull is waterlogged. It is VERY heavy, and the culprits seem to be the through-hull fittings which were never replaced and things bolted to the hull without proper sealing.

It looks like an Alert hull is in order. With that in mind, he's leaning toward the four stroke Mercury 60 EFI. Before he takes the plunge, however, I'd like to solicit opinions regarding the Mercury 60 two-stroke. What are the pro's and con's?

I've seen a number of 16/17 hulls on Cetacea with 50 and 55HP motors. A mix of two and four stroke engines is also represented on those pages. What is the general consensus?


Clark Roberts posted 09-29-2003 05:10 AM ET (US)     Profile for Clark Roberts  Send Email to Clark Roberts     
Paul, see my comments on the Merc 60hp 2S under "Disabeled cyl Cutout..." last post was Sept 15 in this Performance section. Clark
PMUCCIOLO posted 09-29-2003 07:52 AM ET (US)     Profile for PMUCCIOLO    

I appreciate that reference. It sounds as if the Mercury 60 two stroke is hard to beat for the 17' hull. He is sold on the four stroke concept, but I'll relate your experience to him.


Bigshot posted 09-30-2003 03:52 PM ET (US)     Profile for Bigshot  Send Email to Bigshot     
Paul....that alert hull is way heavy(compared to my 1986) for a 60hp.
PMUCCIOLO posted 09-30-2003 06:09 PM ET (US)     Profile for PMUCCIOLO    

Boston Whaler lists the weight of the 17' Alert (equipped with a standard side console and single thwart seat at 1000 pounds). The 17' Montauk weight was listed as 950 pounds.

The boat will be equipped with two 6.6 gallon fuel tanks, a single battery, and the required Coast Guard kit. It won't have a bimini top, swim platform, etc. Also, it will be run primarily alone or with two people aboard.

Please continue with any thoughts on the subject, as the experiences and insights of the forum members are invaluable tools!


PMUCCIOLO posted 11-09-2003 06:08 PM ET (US)     Profile for PMUCCIOLO    
Update: He decided upon the 70HP Johnson (Suzuki) four-stroke EFI. The above input was quite helpful.
Knot at Work posted 11-09-2003 06:32 PM ET (US)     Profile for Knot at Work  Send Email to Knot at Work     

Is there any good fishing over in Jax?

How about ST Johns?

Give me the scoop...

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