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Author Topic:   twins vs. single outboard
james cosby posted 07-15-2003 05:50 PM ET (US)   Profile for james cosby   Send Email to james cosby  
I am having a repower dilemma on my '71 Outrage that I would like to run by the forum. I currently run twin 75 evinrude's that are ready for retirement. I am contemplating on whether to replace with oil injected twin 90 yamaha's or a simgle 175-200 yamaha 2 stroke. I use the boat primarily in freshwater lakes but make an occasional trip to the gulf. I like the idea of twins by having a back-up engine and because they look extra cool, but I also would be interested in the performance of a large single. What do you think? Thanks J.C.

stefan posted 07-15-2003 06:02 PM ET (US)     Profile for stefan  Send Email to stefan     
i just bought an '82 outrage 18' with a yamaha 150

when I'm ready, I plan to switch to twin screws for two reasons
A) always nice to have a back up motor(even if you have sea tow:)
B) boats handle better with twin screws (that's what I 'm told by twin screw owners, and I've sensed it.

How much power are you REALLY losing by using just a stonger single, and is it worth losing A and B?

bsmotril posted 07-15-2003 06:42 PM ET (US)     Profile for bsmotril  Send Email to bsmotril     
Having gone in the other direction, single to twins, I think you will be dissappointed. Twins spoiled me, easier handling, better holeshot, no torque steer, less prop ventilation. Have you considered the Suzuki/Johnson 4 stroke 70? That motor won several design awards, Powerboat reports rated it highly, and they are light for a 4stroker.
timbaho posted 07-15-2003 10:25 PM ET (US)     Profile for timbaho  Send Email to timbaho     
If money's no obstacle (it is around my house) go with the twins but if you are into efficiency (cost over the long haul) then a single with a kicker on the side will get to the hill in a pinch. Kevin
james cosby posted 07-15-2003 10:50 PM ET (US)     Profile for james cosby  Send Email to james cosby     
I agree that the twins is probably the way to go. I really don't like the main with a kicker since it will be nearly the same expense as the twins. I've had a lot of reccomendations to go with the single w/ kicker, for better performance, but the reliability of the twins is nice.
captbone posted 07-16-2003 08:52 AM ET (US)     Profile for captbone  Send Email to captbone     
The single is a better a choice in my opinion. I love the sound, look and feel of twins but on smaller boats it is just for show. I feel that alot of people over rate the extra manuverability of the twins on smaller O/b vessels. The engines are too close together to give you what twins should. Also with motors today, the majority of problems are with either fuel or battery and unless you have dual system (one for each motor) then the twins will fall also. Plus unless they are very large twins, you will not plane on one motor and will get the same speed as a kicker. I feel that a single with hydralic steering, and a 4 stroke high thrust 9.9 kicker with a seperate tank is more reliable and a better system. Just my two cents.
andygere posted 07-16-2003 03:03 PM ET (US)     Profile for andygere  Send Email to andygere     
I agree with the Captain, go with twins only if one of them can put the boat on plane without changing the prop. Otherwise, all you get for your money is a really big kicker. Transom weight on the smaller Outrages must also be considered. Many of today's motors weigh substantially more than those available when these boats were built. Currently, I don't see a viable twin set-up for my Outrage 22 if I were to repower with new motors today. Performance with a single 200 is outstanding, and the 15 hp kicker trolls all day on a gallon or two of gas.
goldstem posted 07-16-2003 03:15 PM ET (US)     Profile for goldstem  Send Email to goldstem     
well, the old outrage can handle about 600 pounds on the stern, since it was designed for twin v4 OMCs. that said, I've always been happy with a single outboard, from cost, maintanence and performance standpoints. My dad had twins, and most failures were fuel related and took out both motors. Now, if I went far offshore, I'd have twins. But I run coastally, and have a good radio instead.

Tom2697 posted 07-16-2003 03:43 PM ET (US)     Profile for Tom2697  Send Email to Tom2697     
My opinion on twins in a small boat is that they look great, but detract from performance. With twins, there is double the drag, more weight (generally), and more headaches. My reasons for the first two drawbacks are obvious. The last one I will explain: Obviously, with two motors being used the same amount of time, there is double the maintenance. There is also more that can go wrong, ie - more parts needed for steering, destroy two props instead of one, etc.

The benefits are there as well but as a few others have stated, unless you separate the two engines entirely, the safety of the 2nd motor does not exist. Contaminated fuel on a single tank vessel will affect both motors. To effectively isolate the motors, twin tanks are needed and each tank must be filled up at a different station to prevent filling with contaminated fuel. This is more work than most people will ever do...definitely more than I want to do.

That is why I repowered with a single engine.

lhg posted 07-16-2003 03:58 PM ET (US)     Profile for lhg    
This is one of those discussions where there is only opinion, no right and wrong. As one who likes twins, here's why, and the issues (truly issues, not problems!!) as I see it.

1. Twins or a single w/pony motor cost about the same! (seriously)

2. Fuel mileage, comparing engines of same vintage, technology and total HP, will be about the same. It simply takes a certain amount of gasoline (energy) to move a boat, and what it's going through does not make much difference. For long periods of idling in no-wake zones,(such as FL ICW) twins are actually better, since one can be shut down and the other run at an efficient 1400-1600 RPM, with no smoke.
Obviously, a pony motor, gives the best trolling economy, if you don't mind the small engine sound on a big boat (I do).

3. You need a little extra HP rating if you go with twins to achieve the same TOP SPEED as a single. As stated, each twin should meet Whaler's recommendation on minimum to plane the boat, or even a little higher. Full HP rating should always be used, or over. Under powering with twins is a disaster. Only underpower with a single.

4. For manuevering,docking, steering, control in big seas, etc, twins will easily outperform the single. You have two rudders and props in the water aiding control. For some reason unknown to me, boats with twins seem to ride better. Maybe it's the increased stern weight.

5. From a design and appearance perspective, the twin engine Whaler looks great, a Class Act, if the engines are well maintained. A single engine Whaler also looks great. A single engine Whaler with a tilted-up pony motor, off the the side, often a different brand, even if it's not banging around on the transom or some aftermarket lift-up bracket, looks crummy and as an after thought. Sorry guys, but that's how I feel. I know, I had such a set-up on my 16 Nauset, and hated it every minute. I hated how it looked, how it performed, and hated running the boat around 99% of the time with the engine tilted up. It's why my next Whaler (18 Outrage) had twins!

Finally, as four stroke and good, smaller DFI engines take over the market, the reason for twins makes even more sense, assumming weight will eventually get under control.

Bigshot posted 07-16-2003 04:03 PM ET (US)     Profile for Bigshot  Send Email to Bigshot     
Well let me tell ya what I think from being on one of those many times but never owning one....basically I don't know Jack.

The boat built in 1971 was designed to handle 200hp. The biggest outboard in 1971 was 125-135hp in both Merc and OMC. In 72 I believe Merc stepped up to 150hp. Was not until 1976 that OMC came out with a 200, next step down was a 135v4. want speed and reliability, ya had to go twins or do 35-40mph with a single.

Janis here has a 1973? with a new 130 Yamaha. She does pretty well, I would say an honest 40mph. The 150 would fetch you another 5-7mph. 200 ponies and you are well above the 50 mark. Would I drop a 200 on one? Only if I knew that 32 year old transom could take what engineers never designed it for. Would I also drop 600lbs of engine on it....sure, but I doubt it. Remember that HP cracks transoms, not weight. Weight effects static trim but those boats are pretty bow heavy to begin with.

My recommendation would be a 150-175hp as light as possible(carbed OMC) or small Yamaha/Merc), if speed is your need. If reliabilty and trolling is, the 140 Suzuki/Johnson 4 stroke would be a great engine. 40+mph and about 5-6gph at cruise.

captbone posted 07-16-2003 04:30 PM ET (US)     Profile for captbone  Send Email to captbone     
The maintaince on twins is twice as much.
phoeker posted 07-16-2003 06:19 PM ET (US)     Profile for phoeker  Send Email to phoeker     
Hello James,

Interesting topic. I just went through the single vs. twins decision making process on my 23 Walkaround and I'd have to say it was very difficult. After a long and thorough investigation, I opted for a single large outboard with a 9.9 high thrust kicker, and I'm absolutely delighted with my decision. Here's why I chose a single/kicker combo:

A single with kicker was $5,200 less than twins, and then add another $450 for prop and $250 for oil tank (for 2 stroke). Remember - It's very difficult to recoup the money you spend on repowering an older vessel when it's time to sell.

Weight of twins: 475 lbs each = 950 lbs at the transom
Weight of single + kicker = 642 lbs at the transom
308 lbs less.

Maintenance & repair: Double the cost of everything with twins. What if you hit a rock or a log on your lake? With a single, you've only got one motor/prop to repair.

Manueverability: I've operated a Grady White with twins. Docking does not get any easier because there is not enough distance separating the props.

With all that said, good luck with your decision. This website is a great place with lots of knowledgable and skilled boaters who will steer you right.

lhg posted 07-16-2003 06:40 PM ET (US)     Profile for lhg    
I think I need to add some facts to my contention that twins cost about the same as a big single with a pony motor. They can, if you're a prudent shopper.

Lets use the 23 Walkaround mentioned above, rated for 400 HP. I'm most familiar with Mercury pricing so I'll use that. But other brands should be equivalent.


A single 250 EFI = $12,500
10 HP 4-stroke = $2,500

Total cost $15,000 plus misc fittings, etc required.
Max boat speed about 40 mph. I think this is minimal HP for a boat this size and weight.


2 - 125 HP 2 strokes = $6300 each

Total cost $12,600, plus about $400 extra for control over cost of single controls

Here, twins, representing same total HP, are clearly less money, although total power would not be quite as good.

OPTION 3: (best, in my opinion)

2 - 150 HP V-6 2 strokes (carbed) = $7500 each

Total cost $15,000 plus the same $400 mentioned above.
Top speed, about 47 MPH.

Perry posted 07-16-2003 08:03 PM ET (US)     Profile for Perry  Send Email to Perry     
Why compare a 250 EFI to carbed twins. For a fair comparison compare 150 EFI's at $10,000 a piece to a 250 EFI at $14,000. Big difference.
lhg posted 07-16-2003 09:18 PM ET (US)     Profile for lhg    
If you must, a pair of Mercury 150 EFI's is an additional $3000, using the examples above, total of $18,000. But you are getting more HP and performance for your $3000. Still a good deal. But why shoot yourself in the foot? A pair of carbed 150's are nothing to complain about, and will outperform the single 250.

One of the reasons the twins are the same price as a single with pony, is that the big engines, all high tech DFI or 4-stroke, are premium priced, where you can get economically priced twins of same total HP rating. Mercury is the only brand that even offers a conventional EFI 2-stroke above 200HP. If you want a classic 2-stroke 225, 250 or 300, you MUST buy Mercury.

On another thread involving re-powering a classic 22, I showed that a single 225 and pony motor, is the same cost as a pair of 115 twins. And this would apply even with all engines being 4-strokes too.

lhg posted 07-16-2003 09:25 PM ET (US)     Profile for lhg    
Further to above, here's another example, using the popular Classic 18 Outrage 2 150HP rating, all carbed engines:


Mercury 150 = $7500
Merc 4-stroke 10 = $2500

Total $10,000


2 - Mercury 75's = $4600/ea
Total cost: $9,200 Twins are actually less here!


2 -Mercury 90's = $5,000/ea
Total Cost: $10,000

This option would give equal or better performance than #1.

jimh posted 07-16-2003 10:35 PM ET (US)     Profile for jimh  Send Email to jimh     
The cost of maintaining twin engines on routine maintenance is probably more than a single plus auxillary, but maybe not.

Twin V-4s would have 8 spark plugs; a V-6 and a kicker about the same, 7-8 plugs.

Replace water pump impeller; you have two lower units to replace in either case.

But here is an advantage with twins: if you have a problem with one engine, you can use the other for comparison. Want to check some voltages? You've got a good engine to use for comparison to the bad engine. Want to swap a part to see if that fixes it? You have a good engine with good parts to test with.

Twin engines enables many kinds of diagnosis strategies when trouble shooting engine problems.

lhg posted 07-16-2003 11:25 PM ET (US)     Profile for lhg    
Jim makes a good point that just helped me out. I had a cooling problem with one engine, and by comparing the gauge readings to the other, I was able to determine a problem.

I also want to say that it makes no difference to me how one powers a boat. There are pluses for both ideas, and my personal boating friends have both types of installations.
On many sized boats, such as the 18-22 Outrages/Revenges, the single + pony is much more popular. But I wanted to at least show that there has been this myth around that twins cost more than a single + pony motor. This is rarely true. I went through all of these calculations when I powered my 18 Outrage, and came up with the same conclusion, 17 years ago.

andygere posted 07-17-2003 01:30 AM ET (US)     Profile for andygere  Send Email to andygere     
I agree that the cost of twins for EFI's or carbed motors is more or less the same as the big single and a kicker, but here in California, the only options are 4-strokes or DFI's. Unfortunately, with twins, the weight penalty is just too much. I have learned from this site that todays "clean" outboards are just too heavy for the 22 hull if twins are selected. My current set up of a carbed Mercury 200 and a Mercury 15 kicker weighs just 483 pounds (406+77), well below the magic 700 pounds suggested as the max by Whaler. I leave the plugs out all the time, and even with 2 batteries and 2 oil tanks in the splashwell, my motor never floods when backing down and my feet are always dry.

Today, to replace the current motors with California legal versions of the same power, that weight goes up to 608 pounds (497+111)for a 200 Optimax and 15 4-stroke kicker. This is still below 700 pounds, but it's like having a 125 pound kid sitting on my outboard all day long. Feet probably stay dry unless there's two of us standing near the stern. If I go with a 4-stroke Merc 200 instead of the Optimax, I'm up to 694 pounds (583+111), right at the limit for transom weight with just a single and a kicker.

Twin 115 Optimax's will put 750 pounds(2x375)on the transom, so my feet are wet, the deck is flooded and I'm using plugs in the sumps and some pumps to keep things dry. The boat looks stern heavy, and I have to repaint my waterlines. Also, I'm nervous because a few recent threads have indicated problems with plug fouling at trolling speeds and overheating when going on plane after extensive idling or low speed running. Whaler says my Outrage 22 Cuddy will plane on 90 hp with a light load, but I don't know if the prop on the twin setup will get me there.

If I go with twin Mercury 115 4-strokes, I'm now hanging a whopping 772 pounds (386x2) off the back, well over the max suggested by Whaler. I've lost my console space by putting my batteries inside it, and the boat looks like it's doing a wheelie at rest.

For simplicity, I've used Mercury in my examples, but I've run the numbers on the other manufacturers and they work out about the same. My conclusion is that if I repower this boat with new outboards in California, a big single and a kicker are the only viable option today. It's too bad, because I do like the idea of twins, especially if a single one will plane the boat and save the trip if one goes down. They also look great, and I imagine improve handling, especially when balancing the boat with an uneven load.

lhg posted 07-17-2003 04:04 PM ET (US)     Profile for lhg    
All of what Andy is saying about engine weight is true, and well thought out, and a problem for the Classic 18-22 Outrages using clean technology. This should make Whaler Drive 20's and 22's increasingly valuable, since they don't have this problem.

The 25's also escape these engine weight issues.

andygere posted 07-17-2003 09:05 PM ET (US)     Profile for andygere  Send Email to andygere     
I'm hoping that by the time my carbed Mercury 200 ('89 vintage) gives up the ghost, the weight problem with mid range DFI and 4-strokes will be solved. It's running strong so I'm happy to just bide my time, but I would like to do some boating on Lake Tahoe before I'm dead. A Whaler Drive model was never an option for me because the LOA would exceed the maximum allowed for my slip, and the wait for a bigger slip is several years.
lhg posted 07-17-2003 09:21 PM ET (US)     Profile for lhg    
Andy - if you take care of it, it will be a long time before the Mercury gives up the ghost! Mine had 2200 hours on them before being stolen, and that's why they got stolen. They looked and ran great.
mustang7nh posted 07-19-2003 09:03 AM ET (US)     Profile for mustang7nh  Send Email to mustang7nh     
How about planing at low speed with twins? Can you keep it on plane at lower speeds with twins? I find that on Long Island Sound I often can't run fast at all so being able to slow it down is valuable. I only have a single but others with the same boat and twins seem to plane 4 mph slower than I can.
bsmotril posted 07-22-2003 03:20 PM ET (US)     Profile for bsmotril  Send Email to bsmotril     
Planing slow iw a big benefit of the twins on my conquestl The double blade area and torque of the motors (Opti 135s) allows planing all the way down to a solid 2800-2900 rpms. But, these are V-6 blocks with the lowest HP rating for that size family which goes up to 175 HP, so they've got plenty of Torque. Curious to see what other say about this same topic with twin 3-4 cyl 70s vs a single 150 V-6.
doobee posted 07-22-2003 08:35 PM ET (US)     Profile for doobee  Send Email to doobee     
Contrary to popular belief, very little consideration was given to specific models of outboard when designing Whalers. The primary consideration was having the right physical dimensions to fit most outboards. Just because a V4 was available at the time does not mean the boat was designed to support the weight of 2 V4s. It would normally take several years to come up with a new hull so it's quite possible that certain engines were not conceived prior to the introduction of a new hull. Once the mold was produced it was too expensive to go back and change it to match new engine models.

Here's my point; if your planning to switch to twins, your first consideratio should be weight. In other words, buy the lightest package that will provide the desired horsepower. In most cases twin four strokes are just too heavy and you'll be dissatisfied with the results.

From my experience, the only models I would recommend twins for are the V hull 18/19 Outrages, the 25' hulls, and all sizes of the Whalerdrive models. (the 20 and 22 whalerdrives will also do fine with a large single). With a Whalerdrive it is possible to increase the horsepower enough to make twin engines worthwhile.

On the smaller boats it is possible to achieve the same horsepower with single or twins. Since the single configuration is lighter, it will offer higher top speed and better economy. The twin configuration will offer a better hole shot and marginally better handling (except for the 18 which sees a substantial improvement due to the spacing of the engines).

In addition to the cost of engines you also have other added costs. You may have to upgrade your steering system to handle the extra weight. A tie bar kit will run you $100 - $200. Then there's extra controls, cables, gages, fuel lines, and of course double the maintenance.

alkar posted 07-01-2004 12:27 AM ET (US)     Profile for alkar  Send Email to alkar     
I have VERY heavy twin Honda 115s (505 lbs each) on my 22' Outrage with whaler drive, and the boat will not plane on one motor with the other tilted free of the water. The static trim is quite aft-heavy, even with two group 27 batteries moved forward of the console.

I thought of repowering with twin Evinrude (Ficht) 135s. That swap would drop the combined motor weight from over 1000 pounds to about 840, while bumping the horsepower about 15%. The Suzuki 140 4-stroke would produce about the same weight/power benefits, but a pair of simple Johnson 2-stroke 115s would net almost a 300 pound weight savings, and that would produce a more normal static trim. The good news is the aft-heavy static trim doesn't seem to adversely effect performance. The folks at Whaler must have known that, as the 1988 model of my boat came with a capacity plate that showed a maximum horsepower rating of 400 - and that requires twin 200s. I think that means whaler expected people to put a pair of 400+ pound motors on the back.

Clark Roberts posted 07-01-2004 06:44 AM ET (US)     Profile for Clark Roberts  Send Email to Clark Roberts     
I can't recommend one over the other (too many variables)but have had two twin engine rigs and many, many with singles. One thing I remember about the twin engine rigs was the hassle of synchronizine the engines (both rpm and trim angle). Seems as though I was always fiddling with the throttles and trim switches (I call it the "fiddle factor") and just when I had everything humming just right I would have to slow down and sync all over again! One of my rigs had a sync light which helped somewhat but mostly I would sync by tachs (not accurate enough) and fine tune by ear. This fiddling thing is a small point but operational ease (smooth and light steering, good wheel and controls/indicators position, proper seating, good vision, low sound levels, etc.) will determine whether your boat is a pleasure or a pain to operate! Twins vs. a single is part of the formula but either can be great or not so great as "the devil's in the details" or at least that's one way to look at it. Happy Whalin'... Clark... Spruce Creek Navy
Plotman posted 07-01-2004 11:22 AM ET (US)     Profile for Plotman  Send Email to Plotman     
I happen to be the proud owner of two different outrage 22s - so I can perhaps offer some apples to apples comparisons about the performance of single versus twins.

My first boat (soon for sale) is a 1987 with a single carbed Merc 200 turning a 15x17" Mercury stainless prop. The other is a 1991 with counter rotating twin Yamaha 130s spinning a pair of Yamaha OEM 13x19" (soon to be 21") cleaver props. The engines are all of similar age, and all run well.

The boat with twins fairly leaps onto a plane - the bow come back down in no more than 2 seconds from a dead stop, and top speed is a touch over 51+ by GPS. With the current props I can wind up past red-line, so I'm going to test 21p. I suspect I will loose a little on hole shot and pick up some additional top end. On just a single engine (with the other trimmed out of the water) the boat planes easily and tops out in the upper 30s at 5400 RPM. I typically cruise ~3800-4300 RPM at 30-35 mph. I find the engines fairly easy to sych by ear, and the ability to trim the engines independantly obviates the need for trim tabs.

The '87 with the single 200 planes more sedately (though certainly adequately), and tops out ~ 42mph, but it has a T-Top which I suspect steals ~3 mph. Oil tank and battery in this boat are in the console, so it sits with a much more neutral static trim than the boat with twins (~445 lbs on the transom, vs at least 800 for the twins including props, a pair of batteries and oil tanks in the splash well.)

I boat in some fairly out-of-the way places (no sea-tow, or anything like it - if you call the coast guard, they will come get you, but leave the boat) on a very unforgiving body of water (Lake Superior - check out live surface temp in the open lake here$station=45006 , so the added security of twins was very, very important to me. If all oif my boating was in well-traveled, warm water locations, I might lean more towards the large single option from a purely practical perspective.


AM posted 07-01-2004 08:17 PM ET (US)     Profile for AM  Send Email to AM     

I´ll put it simple: even if your single engine don´t brake down NEVER, you will ALWAYS go out with more confidence and more relaxed (with twins). And that is why you want to go out in the first place.


galvic posted 10-12-2004 04:58 AM ET (US)     Profile for galvic  Send Email to galvic     
Maybe there is an different angle to the twin outboard issue. With twins you have doubled the thrusting surface, namely the propellers, and you can then choose propellers with greater pitch, which in return will give you greater top speed for given rpms.
Outrage22Cuddy posted 10-12-2004 06:40 PM ET (US)     Profile for Outrage22Cuddy    
I really like the performance of the twins, but I hate the fuel mileage with carb'd 2-strokes. Next repower will be a single 4-stroke.
tpinkerton posted 02-28-2005 10:00 PM ET (US)     Profile for tpinkerton  Send Email to tpinkerton     
I don't have a big Whaler anymore, just an old blue 13 so I guess I'm qualified to join the discussion. My offshore boat is a 21 Cape Horn center console with twin 90's. I've bought a larger walkaround this year with a single large engine and a four-stroke kicker.
A very good source of information on the subject is the Yamaha website. They've tested several boats and post the results for both twin and single installations on identical hulls. The big single wins in both speed and efficiciency, but not by much.
Something that has not been mentioned so far is the cost of rigging beyond the cost of the motors, and it is significant: dual control box, two sets of cabes and gages, tie rod, two props, etc.
Twins cost more all around, no doubt about it. The only real advantage is they look cool and sound cool and that might just be enough if I had more cash. I'm going to miss the sound of those twins, oh boy!
Morro Bay Whaler posted 02-28-2005 11:50 PM ET (US)     Profile for Morro Bay Whaler  Send Email to Morro Bay Whaler     
I bought my new(noncurrent)Yamaha 250 EFI for 10K. I am having a hard time justifying replacing the existing 1985 25hp kicker since it only has 300 hrs on it.

The cost of maintaining a single is much less. First, the kicker usually get much less use and requires less maintenance. Second, on the whole smaller outboards do not have the problems the bigger ones do. Third, the parts for a 9-25hp outboard are cheaper.

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