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Thread: Mercury Sport Jets

  1. #1
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    Default Mercury Sport Jets

    Hello from the Texas Gulf Coast.

    I am exploring the usage of Mercury Sport Jets as an option for extreme shallow water access.

    What are the trade offs of tunnel hulls vs delta pad boats?

    Shallow Running?
    Hole Shot?
    Handling?
    Does the tunnel hull decrease top speed?
    Running grassy areas?

    I have read the Sport Jets are noisy, why is this? Options?
    What may you gain w/ the 250 over the 200?

    I have no experience with the Sport Jet.

    Thanks in advance.

    Eric

  2. #2
    Member chriso's Avatar
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    Default Check the thread "Sportjet boat selection assist needed!‏ "

    There's some discussion about this very question a few threads back called "Sportjet boat selection assist needed!‏" for starters, good luck! SJ's are a great option for shallow performance due to their power to weight ratio.


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    Member chriso's Avatar
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    Quote Originally Posted by scb factory View Post
    Hello from the Texas Gulf Coast.

    I am exploring the usage of Mercury Sport Jets as an option for extreme shallow water access.

    What are the trade offs of tunnel hulls vs delta pad boats?

    Shallow Running? Delta may ride "higher" in the water, tunnel needs less water "under" the boat... I think its about a wash between the two
    Hole Shot? Delta may "lift" a load more readily, more heavy, or quicker, from a standstill
    Handling? Deltas handle great, so do tunnels
    Does the tunnel hull decrease top speed?probably not as much as other more impactful variables
    Running grassy areas? a tunnel may have an advantage to stay clean more readily than a delta in this application

    I have read the Sport Jets are noisy, why is this? Options? Good mufflers, good engine compartment soundproofing, I think my SJ's are quieter than my V-8 boats
    What may you gain w/ the 250 over the 200? low end torque, load lifting capability, (somewhat) fuel economy (somewhat) possibly reliability/longevity, though everyone keeps saying the newer 200's are more reliable than the ones we've owned

    I have no experience with the Sport Jet.

    Thanks in advance.

    Eric

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    Thanks for the input.

    Here a couple of pics of my product. These boats are used to fish the shallow bays and flats of the Gulf Coast. I need 8" to run, 18" to jump up on plane. Draft at rest is 10".

    I plan on building a test boat for the Sport Jet. I know my center pod is wide enough for the jet intake.

    My goal is be able to shut down in ultra shallow water (<12"),and get back on plane. Our bottoms consist of sand, mud, grass. I think elevating the intake a few inches will allow the pump to prime and stay clear of debris.

    Any thoughts on this? What might I expect?

    It should be fun, if it works.

    SCB
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    Member AKBighorn's Avatar
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    There is alot of leverage on that outboard hanging out there like it is. Installing a Sportjet should allow the boat to sit more level at rest. The boat will see a dramatic improvement in handling and manuevers vs an outboard. Be carefull not to put the bow underwater if you stop fast. They are noisy because they are 2 strokes and that imo is made worse when installed inboard on an aluminum boat which is typical in alaska. I am going to experiment with insulating the doghouse and see what effect that has on the noise level on my boat. I wouldnt' think you need the 250hp motor in that boat unless you plan on loading it with alot of weight. My boat (avatar) has the 175hp sportjet and has more than enough power.

  6. #6

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    I don't know a thing about the sportjet but do remember from the years i fished the flats on the upper and coastal bend texas coast all the real fine grass. It seems like thats gonna want to clog the jet up pretty good.

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    We do have alot of sea grasses in our bay systems. Most would be short, much like lawn clippings. I have ran outboard jets, after removing every other grate in the intake , could run just fine. Some guys on the coast run with out any grates.

    The Sport Jet's HydroSurge may be the way to go. We do not have rocks to worry about. How does the stomp grate work for grass? Is it mainly for rocks and sticks?

    I would like to see 60 MPH. The 250 should be my best chance to achieve this. Does this sound realistic? (The main goal is to jump up in <12".)
    Per Mercury Tech: 250 OptiMax, 1350 # Static Thrust
    200 OptiMax, 1100# Static Thrust


    Hull Specs:

    Air-Entrapment, Double Stepped, Mod-Tunnel
    LOA 21' 10"
    Beam 93"
    Weight 1100"

    This is a great forum. Thanks for all the helpfull replies.

    SCB Factory

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    Member chriso's Avatar
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    Quote Originally Posted by scb factory View Post
    We do have alot of sea grasses in our bay systems. Most would be short, much like lawn clippings. I have ran outboard jets, after removing every other grate in the intake , could run just fine. Some guys on the coast run with out any grates. The Sport Jet's HydroSurge may be the way to go. We do not have rocks to worry about. How does the stomp grate work for grass? Is it mainly for rocks and sticks? I would like to see 60 MPH. The 250 should be my best chance to achieve this. Does this sound realistic? (The main goal is to jump up in <12".)
    Per Mercury Tech: 250 OptiMax, 1350 # Static Thrust
    200 OptiMax, 1100# Static Thrust

    Hull Specs:
    Air-Entrapment, Double Stepped, Mod-Tunnel
    LOA 21' 10"
    Beam 93"
    Weight 1100"
    This is a great forum. Thanks for all the helpfull replies.
    SCB Factory
    I've never really paid any attention to how much garbage a SJ will chew up and spit out, if it's smaller pieces of grass like you're describing I think that'd be best odds of it working out ok, they make a "grass" intake that hinges up I assume for allowing a wad of soft stuff to spit through, we've always replaced them immediatly with solid stainless ones to keep from inadvertantly stuff a rock through and tearing something up. I think either one of the 200 or the 250 will give you pretty high odds of making your top speed with your particular hulls, the 250 will probably be better suited for lifting the guy who takes lots of friends and gear with him in the shallows you refer to. We regularly start out in 12" or less water with ours.




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    Member alaskanmoosehunter's Avatar
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    Quote Originally Posted by scb factory View Post
    We do have alot of sea grasses in our bay systems. Most would be short, much like lawn clippings. I have ran outboard jets, after removing every other grate in the intake , could run just fine. Some guys on the coast run with out any grates.

    The Sport Jet's HydroSurge may be the way to go. We do not have rocks to worry about. How does the stomp grate work for grass? Is it mainly for rocks and sticks?

    I would like to see 60 MPH. The 250 should be my best chance to achieve this. Does this sound realistic? (The main goal is to jump up in <12".)
    Per Mercury Tech: 250 OptiMax, 1350 # Static Thrust
    200 OptiMax, 1100# Static Thrust


    Hull Specs:

    Air-Entrapment, Double Stepped, Mod-Tunnel
    LOA 21' 10"
    Beam 93"
    Weight 1100"

    This is a great forum. Thanks for all the helpfull replies.

    SCB Factory
    I hope 60 mph is for open water....

    Runnin' that fast in shallow could get you in trouble real quick like.

    Why so fast? I would believe that a jet trying to attempt those speeds would get the hull out of the water on the slightest chop or waves. I would suspect quite abit of cavitation.
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    Member chriso's Avatar
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    Quote Originally Posted by alaskanmoosehunter View Post
    I hope 60 mph is for open water....

    Runnin' that fast in shallow could get you in trouble real quick like.

    Why so fast? I would believe that a jet trying to attempt those speeds would get the hull out of the water on the slightest chop or waves. I would suspect quite abit of cavitation.
    Or get you a long ways across the stuff with no water on it.


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    Quote Originally Posted by chriso View Post
    Or get you a long ways across the stuff with no water on it.


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    Opps...........
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    Our 17 X Sport will do "about" 63 mph with 2 guys onboard and a 240 Merc Sportjet which is lighter than the newer Optimax SJ's. Thats also a 17 foot boat which weighs right around 1100 lbs ready to run.

    60 Mph with a 250 would be a tall order unless it was in a very light boat.
    I wouldnt be that worried running the shallows at that speed in an alloy boat, In anything else I would be really really worried LOL

    Also if a sand bottom is common you need to be extra careful about running aground. Im sure im not the only member of the board who has put their head through a windscreen after hitting a sand bar and learning the hard way just how fast it can stop a boat lol

    Also just one more thing; for what its worth we (OEM) havent been convinced on the benfits of tunnel designs for our boats and as such do not build them. We feel they limit handling and cause cavitation in situations where you need full pump loading the most(turns in shallow water). Our newest model, the Expedition, in a sport jon format is of a delta bottom design

    Cheers

    p.s. the last video posted was a 21 race tunnel and was travelling at far more than 60 mph
    Skinny water addict

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    The lengths some guys will go to so they can avoid getting their feet wet when getting out of their boats will never cease to amaze me!

    For another vid of some guys with bad luck over 75 mph, check this one out:

    http://www.youtube.com/watch?v=h0utBfPh ... re=related

    I guess no one was hurt... (except the boat) Great sportsmanship from the other competitors huh?



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    Member AK NIMROD's Avatar
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    my 175 sj on a 13 foot boat (1400lbs before i get in) draft 6-8" runs in 1-2" OF WATER i usually prefer knee deep water to start in but depends on bottom. weeds have been a real pain in the past. top speed 50
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    Quote Originally Posted by AK NIMROD View Post
    my 175 sj on a 13 foot boat (1400lbs before i get in) draft 6-8" runs in 1-2" OF WATER i usually prefer knee deep water to start in but depends on bottom. weeds have been a real pain in the past. top speed 50
    That's impressive!
    What hull are you running? Delta Pad?
    What do call "weeds". Hydrilla?

    I think I'm going to like the SportJet.

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    Quote Originally Posted by Xerophobic View Post
    Our 17 X Sport will do "about" 63 mph with 2 guys onboard and a 240 Merc Sportjet which is lighter than the newer Optimax SJ's. Thats also a 17 foot boat which weighs right around 1100 lbs ready to run.

    60 Mph with a 250 would be a tall order unless it was in a very light boat.
    I wouldnt be that worried running the shallows at that speed in an alloy boat, In anything else I would be really really worried LOL

    Also if a sand bottom is common you need to be extra careful about running aground. Im sure im not the only member of the board who has put their head through a windscreen after hitting a sand bar and learning the hard way just how fast it can stop a boat lol

    Also just one more thing; for what its worth we (OEM) havent been convinced on the benfits of tunnel designs for our boats and as such do not build them. We feel they limit handling and cause cavitation in situations where you need full pump loading the most(turns in shallow water). Our newest model, the Expedition, in a sport jon format is of a delta bottom design

    Cheers

    p.s. the last video posted was a 21 race tunnel and was travelling at far more than 60 mph
    Xero-

    I was wondering when you would show up.

    I can build a 1000-1200 # ready to run hull. The wild card is a SJ in my hull design. I would like to see 60, but the main focus is to jump up in less than 12". That is why I am thinking of raising the intake up off the bottom a few inches. I do feel the delta would give better overall performance though.

    What are your thoughs on the SJ in my hull?
    How does the 240 compare to the 250 Opti? Static Thrust?

    I know all about hitting sand bars. I have seen guys thrown out of airboats. Let me tell you, the driver cleared the the bow...

  17. #17
    Member AK NIMROD's Avatar
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    couple pictures of my pride and joy
    bottom is heavy duty; center is 3/8" thick and sides of bottom are 1/4 then whole thing is covered with 1/2" plastic and keel has additional 5/8 " strip 13" wide covering it so it has 1-1/8 thick layer.
    this would not be the type hull you would need down south so you would save on weight.
    i believe it has 8 degree dead rise....do not go with flat bottom. then out on sides it drops back down.... bottom forms a very rough "M" BUT center portion of M is very wide. i'm sure there is a name for that style but i do not know it appearently helps in turning.
    weeds i have had problem with are just a broad grass type....most areas i runn there is not any weeds but when bowfishing for pike i sometimes get in them.
    if i sold mine( and i would ) i would have another made before summer and it would have the optimax engine for fuel ecomony. only reason i would sell it is to get US made hull so i could use it for big game transporting.
    RETIRED U.S.A.F. CAPT.; LIFETIME MEMBER NRA; LIFETIME MEMBER ALASKA BOWHUNTER ASSOC.
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    Member Rob B's Avatar
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    Default Amazing Boat

    AK Nimrod,
    I've seen your boat running up the Sag several times. What an amazing little boat. If you were to sell it, what do you think it would go for?

  19. #19
    Member AK NIMROD's Avatar
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    ROBENTLER-sent you a PM
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