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2014 90hp 4-stroke Yamaha too heavy for 1988 montauk 17
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| Kdellaero |
Posted on 05/17/17 - 8:37 AM
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Just bought a 17' montauk with a 4stroke Yamaha and a buddy tells me this is too heavy and may lead to a cracked transom. Any truth to this?
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| mb466 |
Posted on 05/17/17 - 8:45 AM
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I have a 2005 F90 on a 1984 Montauk. No problems yet... Its been great!
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| JRP |
Posted on 05/17/17 - 8:54 AM
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Over-powering the boat (i.e. going above the HP rating for the hull) would be a more likely cause of damage to the transom.
The weight of the engine is primarily an issue for trim, i.e. causing the stern to squat too much. I don't know the weight of that engine, but it is probably above the original design weight for the Montauk 17 (which was released in the mid-'70s when much lighter 2-stroke engines were the norm.)
Trim can be somewhat corrected by moving other weight forward, for instance by relocating the battery to the center console.
The much lighter Yamaha 70 HP 4-stroke is a popular choice for the Montauk 17.
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| Jetheredge |
Posted on 05/17/17 - 9:50 AM
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I have a 2012 90hp honda 4stroke on my 1987 Montauk and it has been great. no issues.
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| Kdellaero |
Posted on 05/17/17 - 9:53 AM
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The guy I bought it from installed a T top on the boat which I'm not crazy about. I was going to remove it. Is it possible that this was added to offset the weight of the motor, and if so I wonder what impact removing the T top would have?
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| JRP |
Posted on 05/17/17 - 10:31 AM
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Kdellaero wrote:
The guy I bought it from installed a T top on the boat which I'm not crazy about. I was going to remove it. Is it possible that this was added to offset the weight of the motor, and if so I wonder what impact removing the T top would have?
I doubt it. A t-top is a pretty big investment, and there are lots of other good reasons to install one. In other words, that would be an expensive way to address a trim issue.
Would removing it affect the boat's trim? Probably somewhat. Most likely the boat will trim aft and the stern will sit a little lower. Dramatically? Probably not.
There are pros and cons to both T-tops and biminis. I think if I owned a boat where someone had already made the big investment in the t-top, I would keep it (unless it negatively affected storage in a garage, for instance.)
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| Kdellaero |
Posted on 05/17/17 - 10:49 AM
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Thanks for the feedback. To be honest I guess I kind of felt like the boat was a little too small for a T top at 17 feet. I felt like it maybe looked a little goofy.
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| Phil T |
Posted on 05/17/17 - 12:18 PM
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With a heavy motor, you can help reduce the stern squat by moving the battery to the console. Cut a hole in the floor and have the battery sit on the deck.
There are Montauk 17 owners who have T-Tops. It is only a question of properly attaching it to the console and the deck.
The deck does not have backing material for the lag screws so many use a plate welded between the legs to spread the load.
Post some photos here or on a photo site so we can see, admire and advise.
1992 Outrage 17 I
2019 E-TEC 90, Viper 17 2+
2018 Load Rite Elite 18280096VT |
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| Finnegan |
Posted on 05/17/17 - 10:08 PM
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A tee top does not belong on a Montauk, period. The guy who installed had no clue. I would get rid of it. Whaler used to say they can make a small boat like a 1988 Montauk unstable in wind and rough conditions.
Regarding the engine, your buddy is misinformed. For about 5 years, the last years of the classic Montauk through 2002, BW factory installed the "Mercaha" 90 HP 4 stroke on the boat. It had a listed weight of 388#. So we know the boat can handle it. For many years prior to that, people were installing 10 HP kickers on Montauks equipped with 90 HP 2 stroke engines (about 300#), a total weight of around 400#. BW has said the classic Montauk is rated for 410# of engines max.
My Montauk carries a 305# in-line 6 cylinder Merc "tower" very well, with no stern squat at all, and it accelerates out of the hole like a rocket. No transom stress cracks whatsoever.
Edited by Finnegan on 05/17/17 - 10:10 PM |
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| Flounder |
Posted on 05/17/17 - 10:55 PM
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Your 2014 F90 weighs 366 lbs, my 2000 F100 on a same year classic Montauk weighs 356. It's the original motor installed by the Whaler dealer, I've put many hours on it and the transom is still solid so the OP has nothing to worry about. I too would agree with the others that a t top on a Classic Montauk just does not look right. Take it out.
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| JRP |
Posted on 05/18/17 - 5:36 AM
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Finnegan wrote:.....
Regarding the engine, your buddy is misinformed. For about 5 years, the last years of the classic Montauk through 2002, BW factory installed the "Mercaha" 90 HP 4 stroke on the boat. It had a listed weight of 388#. So we know the boat can handle it. For many years prior to that, people were installing 10 HP kickers on Montauks equipped with 90 HP 2 stroke engines (about 300#), a total weight of around 400#. BW has said the classic Montauk is rated for 410# of engines max.
My Montauk carries a 305# in-line 6 cylinder Merc "tower" very well, with no stern squat at all, and it accelerates out of the hole like a rocket. No transom stress cracks whatsoever.
Larry, I'm surprised to read that number (410#) for the Montauk 17. When I contacted BW about the max engine weight for my 19 Outrage II, they told me the max design weight for the Outrage 18 hull was 400#. They were not able to find the spec for my boat, but suggested it should be the same as Outrage 18.
I'm inclined to believe them because my +/-450 lbs Yamaha 150 (with oil tank) puts the scuppers below the waterline. I'd like to think Dougherty didn't intend that!
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| 44thomas44 |
Posted on 05/18/17 - 7:13 AM
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I have an 1988 17 Custom , had an 85hp Evinrude that came on boat when new . Repowered in 2009 with 90 hp Yamaha 4 stroke . Plenty of power , but handled like a dog , transom sat very low in water , plowed bad at lower rpm's (pre-plane ) . Took the 90 4 stroke off , put on my pontoon , bought new old stock Yamaha 2 stroke 90 hp , and now the boat handles like a Porsche . Cruising just above idle speed , the boat sits flat in the water and does not plow . Gas tank (24 gallon ) is mounted under console . Both motors 3 holes up . Much quicker to plane off . I have run that motor ( 2 s ) like a rented mule and it has been FLAWLESS .
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| Finnegan |
Posted on 05/18/17 - 8:47 AM
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JRP - Someone at Whaler gave you the wrong information on the classic Outrage 18. Even in the eighties, almost all 150's weighed more than 400#, and Whaler often showed the boat with twin 70's, or a 150 single and a kicker. These combinations could weigh as much as 550#.
I have twin Merc 90's on mine (305# each), installed on 10" setback jackplates and a battery in each stern corner, and no problems, no stress cracks at all. Here is a photo with my son (150#) adding weight to the stern, plus a loaded Igloo cooler also:
http://smg.photobucket.com/user/lgolt...=6&o=8
Since your Outrage II weighs 600# more than the original, maybe on yours a 150HP 4-stroke at around #450# would be the max? Just don't know on that one.
Edited by Finnegan on 05/18/17 - 8:49 AM |
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| Kdellaero |
Posted on 05/19/17 - 4:18 AM
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It didn't occur to me until after reading some of this but when we put it in at the local boat ramp for a test ride, it was a real struggle to keep the stern from going under the edge of the dock while I was trying to hold it close to the dock. It seemed odd, but I have so little experience with boating that I didn't give it much thought. Could this be a result of having too much weight in the stern, or is this normal?
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| donp |
Posted on 05/19/17 - 4:44 AM
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To be clear. What is meant by a cracked transom?
If spider cracking of the gelcoat is what he is referring too don't be concerned because this doesn't effect the transoms strength.
Also to be clear. Many of us have kicker motors mounted on our transoms which puts the weight in the 400lbs range. If your single motor exceeds this weight than you may have issues but I don't think a cracked transom will be one of them.
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| Kdellaero |
Posted on 05/19/17 - 5:04 AM
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I think I've read enough to give me peace of mind with the transom issue, so I appreciate all the feedback. I'm just curious if it's normal to have to fight to keep the back edge of the boat from drifting under the edge of the dock at boat ramp. I was the only person in the boat and I weigh 155#. It felt like it had more to do with tilting that sitting low but it struck me as strange.
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| Phil T |
Posted on 05/19/17 - 5:17 AM
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K =
Post some photos standing 8' behind the boat showing how it sits at the dock.
1992 Outrage 17 I
2019 E-TEC 90, Viper 17 2+
2018 Load Rite Elite 18280096VT |
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| JRP |
Posted on 05/19/17 - 7:57 AM
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Kdellaero wrote:
I think I've read enough to give me peace of mind with the transom issue, so I appreciate all the feedback. I'm just curious if it's normal to have to fight to keep the back edge of the boat from drifting under the edge of the dock at boat ramp. I was the only person in the boat and I weigh 155#. It felt like it had more to do with tilting that sitting low but it struck me as strange.
There are a lot of variables here, so it's hard to say whether this is normal or not. Is it a floating dock? Is it a fixed dock? What was the tide? Current? Wind?
Also factor that the classic Whaler designs have low freeboard and flat sheer, so will be less likely to match up well with a fixed dock if it is a tall one and/or the tide is out.
Finnegan wrote:
JRP - Someone at Whaler gave you the wrong information on the classic Outrage 18. Even in the eighties, almost all 150's weighed more than 400#, and Whaler often showed the boat with twin 70's, or a 150 single and a kicker. These combinations could weigh as much as 550#.
I have twin Merc 90's on mine (305# each), installed on 10" setback jackplates and a battery in each stern corner, and no problems, no stress cracks at all. Here is a photo with my son (150#) adding weight to the stern, plus a loaded Igloo cooler also:
http://smg.photobucket.com/user/lgolt...=6&o=8
Since your Outrage II weighs 600# more than the original, maybe on yours a 150HP 4-stroke at around #450# would be the max? Just don't know on that one.
Larry,
I absolutely love your Outrage 18 with the twin 90s, plus the optional anchor pulpit. What a beauty.
I did notice, though, that in one of the profile photos the boat is definitely trimmed down noticeably at the stern and up at the bow.
In general, a boat that is trimmed down at the stern will need to climb its way out of a deeper hole to jump up on plane. That will then require more power to achieve the same hole shot as a lighter less powerful engine. It's like a negative feedback loop: More weight causes more squat requiring more power which leads to more weight and so on...
There are some very interesting designs out there that demonstrate this effect, but going in the other direction. A good example is Willian Atkins' Rescue Minor skiff, which is about the same size as a Montauk 17. By keeping the static trim nearly flat and completely avoiding stern squat, Rescue Minor can hop up on plane with a full load with as little as 20 hp, and makes very little wake, too. (It does not attain comparable top speeds, though.)
These classic Whalers, with their relatively narrow beams, seem especially susceptible to stern squat with excess weight on the transom. I would love to have a <400 lbs engine option in the 135+ HP range. The closest to that right now is the Suzuki DF140A, at a little over 400 lbs.
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| Finnegan |
Posted on 05/19/17 - 9:24 AM
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Regarding the Outrage 18 engines, I should have said that with both Yamaha and Mercury, the 70/75's and the 90's are the same weight. so once again these engines fall with in the ability of the hulls to carry the twins. So for the same weights, I always buy the more powerful version. In 1986, when my boat was manufactured, a pair of 1986 Mercury 75's was 550#.
In 1987, a pair of Mercury 75's was 600#.
I would take a pass on the heavy Suzuki 140 , since from every thing I've read its only a 125 HP engine. You would get at least the same power, if not more, from the popular large cube Mercury 115 ProXS at only 359#, also a 125 HP engine.
My 18 Outrage comes up on plane very fast. That is what you get with conventional 2-stroke power.
In the case of this Montauk the tee top may be adding weight to the hull, which could also have a waterlog situation? I suppose it's also possible that Yamaha is under advertising the real correct weight of the engine. It's been known to happen in the past.
I remember an article in a bass boating mag about 10 years ago, where they decided to actually weigh all three of the 225 HP DFI engines from Evinrude, Yamaha and Mercury, to see if the advertised weights were correct. ALL THREE WEIGHED MORE THAN ADVERTISED.
It turned out that Evinrude was the least honest, with the highest weight over advertised, something like 60#. Yamaha was in the middle at about 40#, and Mercury used the least deception, only 15# heavier than advertised. So I guess none of us really know what we're getting. This could apply to boat hulls also. Look at the number of people who have had their rigs weighed on truck scales and find them way more than expected, or what should calculate, based on listed weights of engine and boat.
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| Joe Kriz |
Posted on 05/19/17 - 11:22 AM
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Can we stay on topic here.
2014 90hp 4-stroke Yamaha too heavy for 1988 montauk 17
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