I'm thinking about building a new 20' Open Bow with twin outboard motors. Your thoughts?

[XR6Hurricane]

Personally I think that a twin rig that would be used for slalom should be set up with twin 115s, maybe twin 150s at most. The 300s are heavier, and 600 horsepower could probably get very touchy. Even twin 150s will move the most jaded inboard fanatic to tears with the acceleration.

[vtmecheng]

I know surfing behind an outboard or IO in Virginia is illegal, haven't looked up the law in Pennsylvania.

[Bookm_dano]

Trying to get back on topic... @DynaSkiPete wants my thoughts.... "I'll never go back".

Skied behind many outboards; some of which I owned. It was all fun but it will be all direct drive inboards for me now. I think it will be a hard sell to the slalom crowd.

[eleeski]

The Nautique 196 with ZO is the (irrational Koolaid fueled) standard for slalom pulls. Whatever you build has to feel like a 196 for slalom - even if you have to detune your setup.

 

Speed control matters to an extreme level with tournament skiers. Make something equivalent if you are serious about our market.

 

Honestly, everything else is irrelevant if the pull feels as good or better than the baselines we know.

 

Eric

[DynaSkiPete]

It is interesting to read all your comments. Sadly many are not based on using a well set up modern outboard and driving or skiing behind one. The speed holding of a well set up single motored outboard boat would amaze most of you. A twin motored boat would shock you.

 

We can talk about fuel consumption in a post if you like. The standard NEMA 2000 software and gauges available on modern outboards will give MPG and several other fuel consumption things real time now. Do the inboards do this?

 

I don't expect to sell any boats from this forum. Honestly I don't need to. What I value is information and feedback even the negative ones. We will build bigger boarding platforms. It is a fall project right now. I may build a twin motored open bow outboard. We talked about it again today in the boat shop and will put together the numbers to do it. Obviously the twin motors will mean some compromises and boarding platforms size will suffer. Twin Open Bow may be a play pen type to allow the single fuel tank to be in the nose. Otherwise it will be twin tanks under the front seats. Twin tanks will cost more obviously.

 

I'm going to dig thru my archives and find the old AWSA Boat testing stuff when they tested two old 19' 4" Hydrodynes. They called them 20' but they were 8" short of 20'. Our boats are 20' 1" which eliminated the teeter tottering of some outboards on and off plane at slower speeds. Yes the Hydrodynes used to do this. The 17.6 never suffered from this to the best of my knowledge and a I have a 1987. They were introduced in 1986 and the last ones were made in 1991 or 1992.

 

I'm hoping that some of you take the challenge and slalom behind a ski team twin or triple motored boat sometime. Then tell us about it.

[UWSkier]

@DynaSkiPete you keep going on about speed holding but it's not just about ability to hold speed. I don't think anyone's arguing the point you can make a twin rig feel like a Freightliner. That doesn't make a good slalom boat though. The speed control systems like ZO don't just hold a constant velocity. They allow for a slight variance in velocity as long as the time between certain points in the course is within a given tight tolerance. How it adjusts to skier pull varies based on a skier selecting one of 18 (maybe more?) different settings. When a skier hooks up after a turn, they influence the boat's velocity negatively. The speed control reacts to maintain interval timing tolerance and adds throttle at a specific time, for a specific duration, at a specific intensity based on which of those 18 settings it's programmed with.

 

It's a really complicated system. Just making a twin screw unstoppable force isn't going to get the tourney crowd to sign up.

[skimtb]

Speed control also means being VERY close to a desired speed. Every time. Also how quick it gets exactly there.

No matter how well the twin rig will hold speed, nobody here will be interested if it is 0.5mph off from desired speed and worse yet, if it varies each time a little.

[DynaSkiPete]

I guess I'm having trouble understanding how a speed control system works. Isn't the idea for the boat to remain at a constant speed the whole time thru a slalom course? A jumper needs a solid steady pull to the ramp? Obviously the trick skier wants a constant speed as would a wake boarder? I have to ask a couple inboard owners I know for a demonstration perhaps?

 

As far as the touchy throttle with little or big twin motors. With electronic controls touchy is hardly the case with any motors. It really is throttle by wire. You can easily adjust RPM's by as little as 25 and 50. The gear cases are all the same size on the above 150 motors and the same props can be used on any of them. The only difference will be the motor weight differences which is 530 vs 418 so 102 lbs a motor. 200 lbs on the back of one of my boats is not a huge difference. Putting the fuel tank or tanks in the bow would move more than the weight difference. If we do the batteries that is more weight off the transom area.

 

I found some old AWSA testing scores. The list includes some Hydrodyne Outboards. The higher the score the better it appears. Can anyone guess the year based on the boats tested? I do not know it. My guess is mid 1980's.

 

 

[E_T]

Mastercraft NXT 20 Global edition. It's been done

[Wish]

@DynaSkiPete yes, we want constant speed but not constant throttle. Skiers need the boat to be strong and not get pulled down in speed when we are pulling at our hardest. Assured your rigs won't get pulled down. However, at the same time you don't want the boat to speed up while the pull is non existent during the turning phase of skiing. This is a simplistic description. From any Zero Off equipped boat, you can hear the motor resist the pull by increasing throttle and you can hear the throttle drop off when the skier is in the turn. So all the way down the course, you hear the cruise throttle up and down. In recent years they have added perimeters that the skier can choose as to when the boat revs up and when it lets go so to speak. So not only does the cruise maintain constant speed by holding and releasing the skier, it can be customized to the skiers liking and at the same time, get perfect cours times..aka constant speed for the length of the course. What I think your twin rig would do is hold speed to the point where it won't be very forgiving through and out of the turn as it will still be at full strength. Again, yours most likely will hold speed just fine but that speed is too constant. The choice to make the current cruise systems do this rev release pattern through the course was to assist the skier in the swing from side to side. Like pumping with your legs on an actual swing to get higher on the swing. You pump your legs at the bottom of the swing pendulum or in the skiers case, motor revs up to kick the skier when skier is right behind the boat leaning and pulling. The new cruise systems act like kicking your legs forward propelling you further and more efficiently up to the buoy. Without it, we as skiers actually have to work a little harder as the kick isn't there. Then, the cruise releases us like being at the top end of the swing pendulum, no longer kicking. Your rig would keep kicking so to speak.

[Ilivetoski]

@DynaSkiPete if a boat pulls me at a constant speed of perfectly 36.0 MPH the whole way down the course, that is not a good pull.

[vtmecheng]

Have a demo day. Invite skiers to a course and let them try for themselves. If it's really that good then you won't need to type another post about it, the word will spread on its own. On top of that, you will get great information from skiers about the good and bad.

[andjules]

There's a wild disconnect in this thread. @DynaSkiPete unfortunately you're mostly talking to folks in the top 2-3% of this sport, who want to train with the exact parameters they will be facing in competition, the exact parameters that their peers ski on. They're telling you, of course, that Mercury Speed Control on an outboard ain't gonna do that.

Everybody else remember that at some point you were a 15-off-er. Some of you grew up in the club/private lake environment (in which case, this thread ain't for you) but a lot of us grew up on public lakes, doing a range of towed sports. In fact the gang I skied with up until the last couple of years had a few showskiers as well. If you don't compete, and ski anywhere up to -28/-32 off on public water, your life won't fall apart from not being on zero off. A little experimentation is good for the community. I just had my first set behind a 2019 ski nautique. It was wonderful, but the list price in Canada is very close to what a nice cottage by the lake cost two decades ago. If that's the only possible future of waterskiing, we are in trouble.

[vtmecheng]

Speed control is one part of this thread. The other part is wake and driving. I agree that the person looking for simple water sports fun and casual buoy chaser don't necessarily need zero off (that describes me). We still want a nice wake and a boat that's easy to drive into a course. I keep commenting on these threads because I am the demographic for a Dynaski. I have a family, want to have fun days on the water, but I also want to drive into the course at longer lines. Until I find out how it is in the course I wouldn't even consider it.

 

That all said, I will likely go with an inboard so the prop is under the boat. I've seen someone get cut from kicking a stationary prop, that was not pretty and required too many stitches.

[BraceMaker]

@DynaSkiPete

"Isn't the idea for the boat to remain at a constant speed the whole time thru a slalom course? A jumper needs a solid steady pull to the ramp? Obviously the trick skier wants a constant speed as would a wake boarder? I have to ask a couple inboard owners I know for a demonstration perhaps? "

 

So each of the needs is different,

From a basic perspective against a constant wind a ski boat running a fixed rpm with no skier should hold a constant speed. Problem solved for a boat running with no skier.

But due to the fact that constant RPM means constant thrust any load the slalom skier applies is going to slow the actual speed. The boat will return to speed once that load is removed, but it means that as the skier is going fastest up along the boat the boat is going its slowest.

 

So somehow during the period of time that the skier is loading the boat and before the skier is up along side the boat the engine has to respond to to the increased load. ZO does this by using an accelerometer, the skier picks a profile before they ski which is the engine response curve they prefer (when compared to their pull and how firm essentially) but the end result is that the boat has kept speed.

Jump is its own thing, trick is its own thing. @eleeski for instance has made many references to tricking with Perfect Pass speed controls, prior to their GPS product the Perfect Pass unit was sold with a paddlewheel speed pick up, which would respond to changes in speed, but if you wanted a firmer line PP sold a product known as a jump switch, this was an inline spring loaded contact that would close when the skier pulled over a certain amount of force (compressed the springs/closed the contact breaker) to which the system could respond with throttle. Consider that to be the "predecessor" of what ZO wants to do, or what PP with Z-Box wants to do. Read the load, respond with the appropriate amount of engine response at the appropriate time to not give the skier an overly aggressive throttle response but to also not slow down through the wake crossing.

 

Clear as mud?

[Chef23]

@DynaSkiPete if your objective is to sell your boats to the competition slalom crowd (which is largely the community on this website) you have to have the same pull and feeling that they would get behind a boat they would see at a tournament. That means having ZO or at a minimum PP with Zbox. It isn't a matter of maintaining a steady speed but being skiable and feeling the same as other boats skiers will see in tournaments.

 

If you really want to see if your boat will work for most of the audience of this site try to figure out a way to get ZO in it. Short of that you will never sell your boat over a used DD to most of the users of this site.

[Horton]

@andjules according to my 2017 survey

45% of the reader ship belongs to USAWS

41% ski on private lakes

90% ski on a slalom course

More than 60% run 22 off or shorter

 

To this audience a $70K twin rig outboard is an oddity.

[ALPJr]

Nice find with that chart. Mid 80's would be right based on a couple boats listed. Hydrodyne OB Merc ranked #1. Were they single engine boats? Go for it @DynaSkiPete.

[BrennanKMN]

It is simple physics to me. (Completely made up numbers below)

 

Example 1: A slalom skier directly behind the boat skiing in a straight line requires 100 HP and 150 ft/lbs to maintain 36 MPH

 

Example 2: A slalom skier in a turn at ball 2 requires 75 HP and 100 ft/lbs to maintain 36 MPH

 

Example 3: A slalom skier cutting on edge from 2 ball to 3 ball requires 250 HP and 300 ft/lbs to maintain 36 MPH

 

The size of the motor doesn't matter as long as it can maintain 36 MPH in the worst case. 250 HP and 300 ft/lbs in the examples above. Where speed control matters is how you change between each of the examples above. No matter how much power your motor has it has to adapt to the changing loads. I don't care if you have 1000 HP in your boat, if you resist its forward motion it will require more HP to maintain a consistent speed. How you apply and remove that power is what makes speed control so important. You cannot just slam power on the instant the boat notices a resistance and remove it the second the resistance lets up.

 

I think the gap here is you believe because you have 600 HP the boat won't 'notice' the skier pulling. That is simply untrue. No matter how much power you have any resistance requires more energy to continue forward at the same velocity. More horse power only means that change in power is more granular because you have such excess.

[keithh2oskier]

I kinda feel like the specifics of the the speed control settings are a mute point. Anybody that is that concerned about how close it feels to ZO wouldn't be buying a non AWSA approved towboat in the first place. Wakes alone would feel far enough different than anything your going to see in a tournament.

 

For a recreational boat that is being proposed, a basic cruise control that you can adjust to a single MPH is probably good enough. More important its critical that someone can hop in that has almost no driving experience and operate it. On/Off and a +/- to adjust speed to the MPH. A wally skier doesn't need 18 different settings to adjust while pulling his wife free skiing down a river while trying to make sure the kids aren't throwing the dog out of the boat.

 

I don't think @DynaSkiPete needs to worry about emulating Zero Off when nobody on this forum would ever come across his boat at a tournament.

[DynaSkiPete]

While I don't intend to go the USA Water Ski sanctioning route, one never knows down the line what could happen. Several years ago I was approached about taking a twin to the tow boat testing by a company that could. I passed. People are correct that this group is a small unique group and not one I'd really target. I like the information though and appreciate all your time responding. I do read them all and I have learned a few things. All of you could learn by skiing with a show ski club after all that division is growing so they must be doing something good.

[andjules]

@Horton you may have misunderstood me; I don't disagree: any kind of outboard rig is an oddity to us here; we're a pretty specialized community. I think @DynaSkiPete's ideas are interesting to a level of skier/towed-sports enthusiast broader and below most commenters on this thread; I think both sides of the conversation would do well to keep that in mind and try to have fun thinking in that box and outside ours.

[XR6Hurricane]

@DynaSkiPete I would guess that report was from 1985, because that was the year that Mercury bragged in their brochure that the best all-around rated ski boat was a Dyne powered by a 150 Black Max.

 

[DW]

@DynaSkiPete : as I noted previously, check the speed control threads to get a perspective. Also, review the ZO ABC, 123 calibration charts to get some insight on how the software determines throttle position (since that is all it does) to align the pull characteristic to the skiers preference to the type of pull feel they are interested in. As noted it is not about holding a steady speed, it is about maintaining an average speed (and by average it could be over just a few sampling points) and providing a pull feel that the skier can handle, like, adjust to, etc. and meet a speed tolerance specified by the competition rules.

 

As slightly off topic, we are also somewhat fanatical about rope stretch characteristics but that gives you some perspective on the level of subtlety for this sport at the competitive level.

[DynaSkiPete]

Thanks. A participant in this forum has explained to me in great detail how the various systems work and have progressed. It is interesting and informative. I don't read manuals and most men don't. Slalom skiers really don't want a steady speed. The characteristics of the boat motor adding and reducing power will make it easier to run the course. If the steady pull was from a cable type of system this also would not be ideal for skiers.

 

I have found an owner and user of the Mercury Smart Tow system. He is passively shopping a Dyna-Ski. Hopefully I will learn how this system works from him and the one we are building.

 

I sure wish all slalom skiers would write, email or call Evinrude to encourage them to figured out how to make a system work on their motors or opened the door to one of the speed control manufacturers to do this. Imagine grandpa's pontoon or fishing boat with a speed control system for the grand kids.

[keithh2oskier]

Again I don't know why we are trying to put the latest technology in a boat that shouldn't need it. Its only going to drive cost up which is an unneeded barrier to entry. A bass boat that doesn't even have a ski pylon doesn't need cruise control that mimicks Zero Off. I cant imagine there is any business justification to do so.

[JDM]

This entire thread was a masterful troll job.

[escmanaze]

"I'm hoping that some of you take the challenge and slalom behind a ski team twin or triple motored boat sometime. Then tell us about it."

 

I'm all about it. I would love to try it. Test it out. See if it makes good times. See if my scores are good at all. I'm certainly not against trying something new. For now, and until then though, I am certainly skeptical.

[Ilivetoski]

Most people would be more than willing to ski behind an outboard to try it out, but just out of curiosity have you ever skied or driven an inboard? Don’t mean to sound rude, but I really am not sure. If not, I’m sure someone here would be willing to give you a pull

[liquid d]

I've skied behind probably one of the best slalom outboards ever built, the Glastron Ski Machine. Used it in the course for over a year in my late teens. At the time running 35's at 36 and it was a capable boat in and out of the course.

I'm not sure running twins would be needed at all. For show skiing, the brute power is great, but not slalom.

[DynaSkiPete]

Remember someone asked. I have driven lots of inboards. Frankly they are kind of slow accelerating and on the top end. They feel a little clumsy at times. As for skiing, the larger wakes are better for wake boarding, trick skiing and knee boarding for doing flips off the wakes. WE don't have a slalom course and I have no friends that slalom much so I've never used the speed control systems.

 

I'm not interest in a "pull". If I wanted an inboard even to compare I'd just buy one use it and resell it for testing purposes. I did that to study a Flightcraft outboard when I explored building a similar to it barefoot outboard. It was supposedly one of the best models. The people that were real interested failed to provide the resources or orders to make it happen. I sold it at a profit 3 or 4 years later. Now at age 62+ with spinal stenosis I ski on a pair of big skis. Recovering from surgery to repair a broken right leg (near the hip) is a slow process. I'm hoping to ski again this summer on my pair of skis. Frankly it sucks. The stenosis does not heal. It occurred at age 46. I miss bare footing, jumping (I sucked), free slalom skiing, shoe skis, trick skis, etc.

 

Most slalom tournament skiers will never be happy with an outboard, I get that. This list is slalom skiers still the feedback is interesting. There are also more outboard or former outboard skiers in this group than people realize.

[liquid d]

Build a good inboard boat that matches a 1997 Nautique bubbebutt and you'll have them eating out of your hand!

[Moffattra]

I've always hated outboards, but watching the chaos in the automobile industry and now reading about real electric boats makes me realize it's time for some serious outside the box thinking.

 

So, @DynaSkiPete couple questions:

rope height? i see lots of pics and video of skiing behind your boats, but no one pulling hard. seems like that rope is going to hit the motor?

 

tracking? does the boat have/need tracking fins? especially with the pylon so far back?

[DynaSkiPete]

Boats have a tracking fin. Not good without it.

 

Pylon can be ordered just behind the front seats. No advantage I'm told by owners/users. The pylon can be moved to just in front of the motor well area if someone orders this option in the 17.6 Open Bow.

 

 

The Open Bow 20' actually offers 3 positions: behind the front seats, in front of the sun deck and in front of the motor well behind the sun deck.

 

 

 

I have one picture provided by an owner I will share of someone slaloming behind a 17.6 Open Bow. It is the only picture I have like this I think. It answers the question about height of pylon. The pylon comes in various lengths and has some adjustment via the bracket on the floor. We size it according to the motor height usually.

 

 

[Moffattra]

well, can't say it's for me, but pretty cool, and I bet it works a whole lot better than most of us on here are willing to admit.

[thager]

I had a 76 17.6 Hydrodyne IO with the tracking fin. Tracking was very good. The problem was the side to side rocking caused by the round rear corner hull shape as skier pulled then released. Spooked a lot of my drivers. Straight line rear corner hull shape would probably have eliminated that.

[Ilivetoski]

Why is the passenger seat facing forward in the first picture? Make it pretty difficult to keep an eye on the skier

[Jetsetr]

I like it...but I’m a bit of a “out of the box” thinker...and not a competition skier...

 

[DynaSkiPete]

The old 18' was a foot narrower the the 17.6 & 20 which allowed it tip from side to side more.

 

Our boats can be purchased with a spotter bucket on a swivel or a rear facing bench. I don't understand why anyone would want to ride around the lake not being able to look forward when not pulling skiers. I'd never own a boat with a rear facing front bench. Very old school, single purpose design but cheaper and easier to make.

[keithh2oskier]

@DynaSkiPete The fixed bench allows more seating in a traditional closed bow ski boat. Remember with the pylon in the front of the engine the rear seat is useless with a skier so you only have space for the driver and the passenger seat. If you put that as a swivel seat that only allows one person. Where a fixed bench can fit two.

[DW]

@DynaSkiPete : you might actually be surprised at the advantages of a rear facing seat offers. More seating space, more storage space, much better eye to contact with the driver, nice view out the rear. That setup is actually pretty darn nice to take the 'squeeze' on a slow sunset cruise. Suggesting the entire tourney ski boat market offers only an old school option indicates more research may be needed for you to fully understand the market.

[DynaSkiPete]

So you don't think I know the "advantages". That is funny. My wife likes the swivel bucket, hates the bench. Case closed. Really stretching it guys to justify an old school, old style design. Flexibility to get exactly what the customer wants is the new norm. Some manufacturers are scratching to make improvements every year to get folks to part with a lot of money to replace the old "outdated" boats. Since either seat can be ordered this is the best solution.

 

It may not be long before a plain old direct drive is hard to get as the wake surfers and such become the market. The large public lake I live on has several inboards with towers. The owners mainly pull tubers. I'm seeing more and more Zup board users. Way more show skiers mainly swivel skiers than slalom skiers. In fact if there is one slalom skier a week I'd be surprised. Granted I'm not here on about half of the weekends and many week days it is very slow on the lake which is the beauty of this like.

[BraceMaker]

I sit 2-3 people on my bench. Can't do that with a swivel.

[liquid d]

As Master Po once said "It is time for you to leave."

[Ilivetoski]

When I see a bucket seat I just can’t help but think someone thought “how do we make the boat look cheap, inefficient with seating space, and inefficent with storage space... wait, I have an idea” seating is already limited in a ski boat, and dyna-skis don’t look to have any more seating than an OB direct drive... not much reason to listen to me, I’m not now nor ever will be in the outboard ski boat market but it’s just my $.02

[Drago]

This is weird

[Killer]

I must be crazy to think of all the $150k wake boats they sell with rear facing seats... Pete’s old lady won’t be having it! Lol

[vtmecheng]

Please refer to the first comment in this thread.

[oldjeep]

@DynaSkiPete fwiw malibu used to offer dual rotating front buckets in many of its v drives. Pretty much nobody wanted it and you see very few on the water.

[liquid d]

The school has turned, the feeding frenzy starts....it's Shark Week!