Quick Answer The Mercury 90 HP FourStroke is the default pick for most 16, 18 ft aluminum fishing boats and mid-size pontoons up to about 22 ft in Ontario. It runs on the same 2.1L inline-4 block as the 75 and 115, weighs 359 lbs, and is tuned for smooth cruising and fuel...
Quick Answer
The Mercury 90 HP FourStroke is the default pick for most 16, 18 ft aluminum fishing boats and mid-size pontoons up to about 22 ft in Ontario. It runs on the same 2.1L inline-4 block as the 75 and 115, weighs 359 lbs, and is tuned for smooth cruising and fuel economy rather than performance. For pontoons, take the Command Thrust (CT) version. For aluminum fishing boats, take the standard gearcase.
Mercury 90 HP FourStroke Review
We sell more Mercury motors in the 75, 115 HP family than any other class. And within that family, the 90 is where most customers end up, not because it's the cheapest option, and not because we steer people there, but because it's genuinely the right fit for most Ontario boats in the 16, 20 ft range.
Harris Boat Works has been selling and servicing Mercury outboards on Rice Lake since 1947. We're a third-generation family marina and a Mercury Marine Platinum dealer. The 90 FourStroke is a motor we know well, and one we're honest about when it's the wrong call.
What the 90 HP Family Actually Shares
The Mercury 90 HP FourStroke is part of a five-motor family built on the same 2.1L inline-4 block: the 75, 80, 90, 100, and 115. All use an 8-valve single overhead cam with a maintenance-free valve train, no regular cam service, no valve lash adjustments for the life of the motor. Mercury ran 17,000 hours of factory testing on this generation before shipping.
The differences between the 90, 100, and 115 are tuning, RPM ceiling, and price. There is no weight penalty as you step up. The 90 ELPT and the 115 ELPT both weigh 359 lbs.
The motors covered in this post are the standard 90 ELPT FourStroke and the 90 ELPT Command Thrust. There are also a counter-rotation 90 (for twin setups) and a 90 EXLPT (25" shaft for taller transoms). Different SKUs, different prices, different applications.
What "ELPT" and "CT" Mean
- E, Electric start (push-button, not pull cord)
- L, Long shaft (20"), fits the most common transom
- PT, Power trim and tilt, you trim the motor up and down from the helm
- CT, Command Thrust gearcase, larger lower unit, bigger prop swing
Where the 90 HP Is the Right Answer
16, 18 ft aluminum fishing boats
Lund, Princecraft, Crestliner, Legend ProSport, these are the hulls the 90 ELPT was built for. Typical load: two to four people, full gear, trolling motor, a couple of batteries. On those boats, the 90 planes cleanly, cruises around 28, 32 mph, and tops out around 38, 42 mph depending on prop and load. It has headroom for the occasional full boat.
Mid-size pontoons up to ~22 ft
For a pontoon carrying four to six people with normal cottage loads, the 90 ELPT Command Thrust is the call. The CT gearcase swings a 14 or 14.5" prop instead of the standard 13", which translates directly to hole-shot on a flat-bottom hull. Standard gearcase pontoon 90s are slower to plane and work harder doing it.
Family runabouts in the 16, 18 ft fibreglass range
Cruising, towing a tube, swimming, occasional fishing, the 90 handles all of it without working hard.
Repowers replacing 70, 90 HP two-strokes
Older Mercury, Yamaha, and OMC two-strokes in this power class are being replaced every season. The 90 ELPT FourStroke typically comes out lighter than the motor it's replacing, quieter, cleaner, and 20, 30% more fuel-efficient for the same day on the water. Most owners say the boat runs better than it did when new.
Where the 90 HP Is the Wrong Call
Hull rated under 75 HP. The capacity plate is the ceiling. A 16 ft aluminum boat rated for 75 HP max should get the 75, not the 90. We can order a 75 if the plate forces it.
Heavy tritoons, 24+ ft pontoons, or houseboats. The 90 will push those boats, but it'll work harder than it should for its service life. Those applications need 115 CT or higher.
Bass-boat hole-shot. The 90 ELPT FourStroke is not a Pro XS. It's tuned for fuel economy, smooth cruising, and durability. If you want strong off-the-dock acceleration on a 19 ft fishing boat, the conversation shifts to a 90 Pro XS or a 115 Pro XS.
Mismatched shaft length. A short shaft (15") on a 20" transom puts the prop too close to the surface. The motor won't cool properly, and you'll ventilate. Shaft length must match transom height. Measure before you order, or let us measure for you.
You can build a live CAD quote for your repower online at Mercury Repower Centre.
Standard Gearcase vs. Command Thrust
|
Standard Gearcase |
Command Thrust |
| Gearcase profile |
Hydrodynamic, lower drag at speed |
Physically larger |
| Prop size |
~13" |
14, 14.5" |
| Strength |
Top-end speed, fuel efficiency |
Low-end thrust, hole-shot |
| Best for |
Aluminum fishing boats, lighter runabouts |
Pontoons, heavy hulls, boats that struggle to plane |
Rule of thumb: aluminum fishing boats default to standard. Pontoons default to CT. Heavy or unusual hulls, tell us the load and use case before we recommend.
How the 90 Compares to the 75 and the 115
The 75, 90, and 115 are the same block with different tuning. There is no weight penalty stepping up. The only real penalty going from 75 to 90 to 115 is price and fuel burn at full throttle.
Most boats want either the 90 or the 115. The 75 is right for smaller hulls or situations where the capacity plate forces it, we don't actually stock the 75 because the 90 is the same physical motor at a small additional cost and has better headroom and better resale value.
If you're already shopping the 90 and wondering about the 115: the step from 90 to 115 is tuning, not a different motor. There's no weight change. For a 17, 18 ft aluminum fishing boat that will regularly carry four adults and full gear, the 115 is worth considering. For a 16 ft boat running two anglers, the 90 is the right call and the 115 is extra motor you won't use.
What We'd Actually Recommend
For most 16, 18 ft aluminum fishing boats on Rice Lake and the Kawarthas: 90 ELPT FourStroke, standard gearcase.
For mid-size pontoons up to 22 ft: 90 ELPT Command Thrust.
For heavy loads on an 18, 20 ft boat: Consider the 115 ELPT instead.
If the hull is rated under 75 HP: We'll order the 75. We're not going to put an illegal motor on your boat.
If you buy from us, we're also the ones servicing it. For engine repairs, we only service Mercury and Mercruiser, no farmed-out repairs, no strangers touching your motor.
Related guides
Prices shown reflect HBW's current Mercury dealer pricing. For live updates as Mercury issues new dealer pricing, see our Mercury pricing reference.
Frequently Asked Questions
Is the 90 HP good for a 22 ft pontoon?
Yes, with the Command Thrust gearcase. Standard gearcase on a 22 ft pontoon is undersized for typical cottage loads. If the pontoon is a tritoon or you're carrying six people regularly, consider the 115 CT.
Is the 90 HP FourStroke a Pro XS?
No. The Pro XS is a different tuning, higher RPM ceiling, sport gearcase, more aggressive hole-shot. The standard 90 ELPT FourStroke is tuned for smooth cruising and fuel economy.
Does shaft length matter?
Yes, it's not optional. A short shaft on a 20" transom puts the prop too shallow to cool the motor properly. We measure every transom that comes through the shop.
How much does the 90 HP save on fuel vs. an old two-stroke?
Typically 20, 30% less fuel for the same day on the water. The exact number depends on the old motor's condition and how you use the boat.
Is the 90 CT the same motor as the 90 standard?
Same powerhead. Different gearcase. Different SKU, different price, different prop size, and often a different recommendation depending on your hull.
Can I order a 75 if my capacity plate requires it?
Yes. We'll order whatever the plate allows and not try to talk you into something you can't legally put on your boat.
Build a Quote
Build your 90 HP quote at mercuryrepower.ca, pick the standard or CT gearcase, shaft length, and prop. See real CAD pricing in minutes.
Questions? Call 905-342-2153 or submit a service request at hbw.wiki/service.
Harris Boat Works, 5369 Harris Boat Works Rd, Gores Landing, ON K0K 2E0.
Related guides: Mercury 75 HP FourStroke, why we don't stock it | Mercury 115 HP FourStroke review | Mercury 40 vs 60 HP | Ontario Mercury Outboard Price Guide
Ready to price it out? Build a live CAD quote for your repower online at the Mercury Repower Centre.
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