Skiboat prop wash

[Andre]

And the fight begin!  Tree huggers neighbors want to get rid of motor boat on my lake and we have to get organize. Our lake is shallow and the course is in 9 to 13' of water.They claim we are stirring up the mud and putting back sediment and phosporous  bla bla bla...

Anyone knows of any studies on skiboat and how deep the prop wash can go ?

 

[Jody_Seal]

9'-13' is pretty deep as ski lakes go. i do know running of ski boats promotes water aeration.

Dang those Do-gooders causing issues. where is this happening?

[MDB1056]

looks like he's Canada 

[03RLXi]

Use a drone and see if there's any colour change when take off. Once skiing it'd be minimal compared to first pull. (Surf boats would direct their trust downwards all the time)

[Killer]

1 hour ago, Andre said:

And the fight begin!  Tree huggers neighbors want to get rid of motor boat on my lake and we have to get organize. Our lake is shallow and the course is in 9 to 13' of water.They claim we are stirring up the mud and putting back sediment and phosporous  bla bla bla...

Anyone knows of any studies on skiboat and how deep the prop wash can go ?

 

Is the lake managed by any government entity?   Transport Canada manages most waterways and where my place is in Ontario the township has some jurisdiction as well.  It would take a lot of political interference to make such a massive change. 

Waterways are public entities, anyone can access them.  Since you have property on the water, assuming you can launch your boat, there's not much anyone can do to stop you.

The ski course is a seperate issue, I was told by transport Canada that if the lake owners association doesn't want the course, it needs to be removed, even if you have a permit, baring major legal battles...

Yes you need to organize.  Go to every homeowner who has a boat... Be nice 🙂

[Killer]

10 minutes ago, 03RLXi said:

Use a drone and see if there's any colour change when take off. Once skiing it'd be minimal compared to first pull. (Surf boats would direct their trust downwards all the time)

They definitely do stir up the bottom.  At least to 3 or 4' depth.  So does swimming though....

[Horton]

Sure a ski boat moves some goop around on the bottom of a 13' lake. Very much? No. 

Wind pushes the top of layer of water with the wind direction and the bottom layer of water against the direction of the wind. That also mixes up a lake.

All kinds of natural and man made factors mix up a lake and often that is a good thing for the ecosystem of a lake.

[chrislandy]

I would have thought the Canadian Waterski and Wakeboard Assoc should have some info on this

[2Valve]

15 hours ago, Andre said:

And the fight begin!  Tree huggers neighbors want to get rid of motor boat on my lake and we have to get organize. Our lake is shallow and the course is in 9 to 13' of water.They claim we are stirring up the mud and putting back sediment and phosporous  bla bla bla...

Anyone knows of any studies on skiboat and how deep the prop wash can go ?

 

Tell the guy to breathe 25% less air a day. Make him do his part to reduce his CO emissions.

[skibrain]

Sounds to me like they are picking or inventing an issue.  Is their concern really water quality?
 

Or are they annoyed with boat noise, traffic patterns, or hours of power boat activity, etc?  Sometimes people are truly unreasonable. But before battle lines are drawn, I’ve found a conversation can lead to a workable compromise or problem solving. 

 

[Killer]

5 hours ago, chrislandy said:

I would have thought the Canadian Waterski and Wakeboard Assoc should have some info on this

Totally out of its jurisdiction.

[Horton]

regardless of the facts, I assume we're going to blame Canada?

[chrislandy]

1 hour ago, Killer said:

Totally out of its jurisdiction.

OK, whoevers countries water ski association...

For example, the BWSW (british water ski) has information that can be used in impact assessments when trying to open a new site or keep one from closing (whether you can talk to the right person might be another story!)

[Sethro]

There are lots of studies out there regarding wake boat damage, and it usually includes "normal" boat traffic as a comparison.  That would be a good place to start.

 

[RAWSki]

You need a lake/aquatic specialist with real knowledge and experience, who can debunk fact from fiction.  

Something similar happened to us 20 years ago when we wanted to change how we managed our lake weeds.  Lots of crazy assumptions were made without any real facts.

"putting back sediment and phosporous" is the first red flag, phosphorous generally comes from run-off into the lake and the most common cause is from home-owners using fertilizers on their lawns.  

Mis-information is  your worst enemy. Good Luck

[MitchellM]

36 minutes ago, RAWSki said:

 

"putting back sediment and phosporous" is the first red flag, phosphorous generally comes from run-off into the lake and the most common cause is from home-owners using fertilizers on their lawns.  

Mis-information is  your worst enemy. Good Luck

Agreed.  That sounds like a total fabrication with no scientific basis.  Exactly how does prop wash affect the phosphorous level in a lake?  These nutrients come almost exclusively from fertilizer run-off from lakefront lawns.  A better effort to tackle this problem would be to ban residential fertilizer use.

Sounds like a neighbor who just doesn't like power boats on the lake.

[skibrain]

Not trying to push a thread tangent, just the idea.

We installed a fresh air exhaust on my buddy’s boat and modified our turn spin by a couple hundred feet at one end of the course.

it addressed an influential lake neighbor’s gripe about early slalom skiers on a public lake. Yeah, we had full right to be there, but we tried to understand this guys motivation to change boating hours.

Loud pipes don’t save lives. They just annoy people.
 

 

[DW]

Given the timing one could assume the complainant is using some of the wake boat studies to push their assumption.  The U of Minnesota study is the only one that attempts to use a ski boat in the comparison that I have found.  It does not address turbulence depth from the propwash.  From pure visual observation my analysis points toward no significant impact at depths exceeding ~ 6'.  I moved my lift a couple of years ago and the sediment under and behind the boat has not been cleared over the 2 years which includes at least 200+ lift entries and that would be less than 4' depth.  It is very interesting that when we ski, the birds tend to come towards the boat to look for prey, one could extrapolate the prop wash actually is good for lake health.

As noted, phosphorus is from lawn fertilizer, I don't believe aeration is a contributor.  Invasive species are a much more egregious problem in the Great Lakes region, of which water fowl and non resident boats are the significant contributors.

There are several lake management companies and active universities that probably can provide good and 'accepted' insight.  Good luck.

[Killer]

3 hours ago, chrislandy said:

OK, whoevers countries water ski association...

For example, the BWSW (british water ski) has information that can be used in impact assessments when trying to open a new site or keep one from closing (whether you can talk to the right person might be another story!)

 

3 hours ago, chrislandy said:

OK, whoevers countries water ski association...

For example, the BWSW (british water ski) has information that can be used in impact assessments when trying to open a new site or keep one from closing (whether you can talk to the right person might be another story!)

It's in Canada but boats being allowed on lakes has nothing to do with Waterski Canada.  There are reasources they can provide with respect to setting up courses, but even that is quite limited. 

 

[jpwhit]

@Andre who controls the lake? Who will have the authority to decide the outcome? How does that process work?

I'm not sure you're going to find enough credible information to argue against their claim. I wonder if the better approach is to press them to prove their claim in a credible fashion. If they are basing their claims on research for a different kind of boat than ski boats, then it shouldn't be too hard to explain why that's invalid. 

But again a lot depends on the answers to my first question about what the process is for changing the rules for the lake. 

[Kelvin]

I live on a lake that's 7.5ft deep with about 18 inches of silt below that.  Our lake has ski boats, wakeboard boats and surf boats.  The ski boats never churn up the silt on the bottom, but many of the surf boats leave a chocolate milk trail behind them from churning up the silt.  On the other lakes in the neighborhood that are 6ft deep, all of the surf boats churn up the silt.

[Andre]

As for all water in Canada,federal laws apply. But the law will change soon to give the power to provincial and towns to regulate lakes and rivers to facilitate new lakes\boating rules according to each case. Lake is not natural,they built a dam longtime ago for a papermill hydro,not in use anymore. So no springs or underground water source.Most of the water is coming from 2 small rivers that run along LOT of farmland.That' s the biggest cause of phosphorus in the lake.

It's not done yet but we have to organize cause this guy is a retired pharmacist,very bright and with a lot of free time.He hate PWC with a passion and started a petition to ban them in 2016 with no success.

The news of his project has cause quite a commotion here.

In the far-west, he would be hanging from the highest tree at the town limits...

Edit:Lawn fertilizer have been banned for more then 10 years around the lake.

Thanks to all!

[chrislandy]

14 hours ago, Killer said:

 

It's in Canada but boats being allowed on lakes has nothing to do with Waterski Canada.  There are reasources they can provide with respect to setting up courses, but even that is quite limited. 

 

Same as in the UK, but they should be able to point you towards studies, specialists etc and they "should" be acting like a lobby group for the sport so hopefully they would be able to assist against any threat to the sport

[208maverick]

I think the simplest and most direct way to combat this is to put a GoPro about 3' off the bottom and actively film what's taking place as a ski boat goes over top.  I don't think you're going to see much bottom disturbance at all, but film would give you some pretty good stuff to work with.  If any of your ski group has scuba gear, about 30 minutes of playing around finding the right location, depth, etc... should give you everything you need.   

[DW]

Prop wash is a powerful force, data is not readily available for the watersports community, plenty of it under lock and key for military applications.  The depth will be directly related to prop angle in motion, torque input to prop, prop speed, etc.  There will be a significant depth difference between a ski boat on plane v a heavily laden wake boat at peak surf wave attitude.  Maverick's suggestion above is a logical, low cost method of trying to capture some data although people will be free to interpret it as they wish.   It is a topic starting to see discussion with the wake boat issues and property owner complaints on erosion, property destruction, etc.  Facts are a hard thing when the opposition argument is very emotional.

No data from the paper although several references are included:  https://www.sciencedirect.com/science/article/abs/pii/S0029801813002989

Some visuals included in this one:  https://www.sva-potsdam.de/en/adm-juli-2016/

I would research any potential University studies for data, that is probably to best source of available, low cost (free) information containing facts.