# Pathfinder 17 Tunnel



## jlo86cj (Dec 22, 2011)

Knowing TX is the king of tunnel boats, I figured this was the best place to look for experiences with the PF 17 Tunnel.

I'm running a Yamaha 60 2-stroke, Bob's 4" setback jackplate. PT RXB4 prop and Lenco tabs. It wont get on plane (or stay on) with the plate higher than 2". I just bought a PT SWW3 to see how that works.

Any other pointers would be appreciated...

Thanks,
Jimmy


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## JimD (May 25, 2004)

Put a picture of the boat and motor setup if you will.


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## jlo86cj (Dec 22, 2011)

This is what I have for pics. I'll take some close ups of the tunnel when I get it back from the shop.


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## Flat's Hunter (Oct 18, 2007)

When try to get up. How do you have you motor trimmed? All the way in? Also when you say won't stay on plane what happens when you raise the jackplate? Does the prop lose grip and revving up. Tell us more about what happens and how you have motor trimmed in these situations


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## Stuart (May 21, 2004)

I don't recall ever seeing a jackplate on that hull. Just saying. With the built up transom most people don't put one on there.


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## jlo86cj (Dec 22, 2011)

When trying to get up, it's trimmed all the way down and if the jackplate is higher than 2" it revs up, cavitates and won't get on plane. When up and running (trimmed up slightly) if I raise it over 2 it looses grip, revs up and starts coming off plane.

The RXB4 is vented and has about 2" to much pitch (16). The SWW3 I just got should be a better pitch (14).


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## baynick (Oct 14, 2009)

I had a 17" pathfinder with a jack plate. I found that you need to run the motor at about 5600 rpm max. A three blade gave me better economy but less shallow water performance. They say that you can reduce or increase your rpms (typically) by 200 rpm per 1" of pitch. The four blade should hold the water better and not blow out, but you might need additional cup. 

So, if you are getting close to your maximum rpms with the four blade , I would think that all you need is an additional cup (heavy cupped) to keep the prop from Blowing out ( cavitating ).

And another helpful addition might be to install shims at the jack plate to hull mounting. These shims add an additional "leaning" or degree of motor to your already agressive transom. They are easy to install and pretty cheap, or you could add washers to the top bolts to get the "lean" you want, but I recommend the shims. They give you more support all the way down the transom to jack plate abuttment.

I would first try the 4 blade prop at the correct rpm, with an agressive cup.

Hope this helps,

baynick


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## BBKing (May 22, 2010)

I don't think wedges (shims) will help. With the aggressive rake on that transom you should be able tuck the motor in far enough. Also, the fact that you state that you can't lift the motor more than the 2 inch position after you are on plane, would indicate that wedges would not solve your problem. A shallowblaster or similar anti-ventilation plate should help; however, my guess is you need to work on the prop as Baynick has suggested. There are some good prop shops out there that should be able to help.


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## That Robbie Guy (Aug 11, 2009)

I have no help to offer ... 
but would like to say man, that's a good lookin' rig!


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## jlo86cj (Dec 22, 2011)

I actually put 5deg of negative wedge in because the transom was so wedged I was at the end of the trim rams when the cav plate was parallel to the bottom. Before installing the neg wedge I did a lot of testing and had no benefit from the increased tuck in. You can see from the profile pic it still has a lot of wedge even after installing the 5deg neg wedges.

This is the 16 pitch prop I've been running and getting around 5000-5200 rpms with.

*RXB4*
_13.25" DIAMETER, AVAILABLE IN 12"-21" PITCH, 4 BLADES, RIGHT- AND LEFT-HAND ROTATION, MODERATE RAKE AND CUP, ACCELERATOR SERIES OF HOLESHOT/HANDLING PROPS, EXCELLENT ALL-AROUND 4-BLADE - SATIN FINISH SHOWN - POLISHED FINISH AVAILABLE_









I spoke to Marcus at Powertech and all he could compare it to was the Maverick HPX17 Tunnel (with jackplate). He said they tried an SWW3 and SWW4 on the Maverick and the 4 blade was blowing out and the 3 worked much better. They "thought" the 4 blade may be sucking the tunnel dry. Not sure if that's the case but I decide to try the SWW3 to be on the safe side. Here's the info on the SWW3 & 4.

*SWW3*
_13.5" DIAMETER, AVAILABLE IN 12"-17" PITCH, 3 BLADES, RIGHT-HAND ROTATION, EXCELLENT GRIP FOR MOTOR ELEVATION AND CAVITATION-PRONE APPLICATIONS - SATIN FINISH SHOWN_









*SWW4*
_13.5" DIAMETER, AVAILABLE IN 14"-16" PITCH, 4-BLADES, RIGHT-HAND ROTATION, 4-BLADE VERSION OF SWW3, EXCELLENT GRIP FOR MOTOR ELEVATION AND CAVITATION-PRONE APPLICATIONS - POLISHED FINISH SHOWN_









I have been thinking of trying a ShawWing (small) compression plate after I see how the new prop works and was wondering if anyone had tried one on this hull.

Thanks,
Jimmy


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## Flat's Hunter (Oct 18, 2007)

When the prop blows out it is not cavitating. It is ventilating, meaning it is losing grip with water and filling prop area with air. Cavitation has to do with pressures and boiling of water. A shaw wing could help with your problem for sure. Your negative trim looks fine. 

Jack plate setting doesn't really mean anything because it is relative. Take a picture from behind of boat so we can see where the prop is in relation to the tunnel when plate is down, at number 2 and all the way up. You may have motor hung to high

Also. Your prop needs to run at max motor rpms at WOT. old old one was to high a pitch. Design of prop can change rpms too as well as pitch and # of blades

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## Flat's Hunter (Oct 18, 2007)

I saw where you already realize your prop was pitched to high. One other thought, at least on take off is the vented prop could be hurting you. Don't know a lot about venting but could be over revving the prop perhaps 


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## BBKing (May 22, 2010)

Yeah, usually when we refer to cavitation we really mean ventilation. The high and low pressures caused by the prop moving through water causes gases to be released from the water. That process is termed "cavitation". These gases, created by the low pressures,when recompressed by the high pressure can actually explode and cause damage to the prop (pitting). The props on submarines are designed to minimize cavitation primarily to reduce noise. 

Ventilation occurs when the prop starts sucking air which often happens when the prop is near the surface. An anti-ventilation plate, which is usually referred to in error as a cavitation plate, should help. However, as I mentioned before, I think you need some work on your prop. I think a clever type prop could be the solution since they are designed to run near the surface. That, combined with an anti-ventilation plate should fix your problem.

I had a PT prop which looked very much like yours and it did not work at all on my Baby Cat. The clever prop made more improvement than I would ever had hoped for.

You do have a nice boat there; do they still make that model?


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## Bayman (Oct 18, 2004)

I agree with Flats. With the raised transom and the addition of the jackplate, your motor is running really high. I can't tell exactly from the pictures, but it looks like your prop is running quite a bit higher than the tunnel. Like Flats said, "the number on the plate is relative to the position of the moter." If you had a flat transom, the plate would actually be running in the 6-8" range before you had this problem.


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## Bruce J (Jun 27, 2004)

Try the SWW3 first and let us know how it works. I've got that same prop on my Maverick HPX-T with a jackplate and 70hp Yamaha (and I'm probably the guy Marcus was talking about since he helped me with my prop). This prop works well on my boat. It keeps it's grip up to the top of the jack plate range.


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## jlo86cj (Dec 22, 2011)

I finally got the boat out of the shop and was able to run it a little with the new prop today. The SWW3 made all the difference. I can get on plane with the jack plate all the way up and can trim it up once on plane without ventilating or losing water pressure.

Here's a rear shot with the jack plate down and trim tucked in.










Jack plate down with cavitation plate parallel to bottom of hull.



















Jack plate all the way up with cavitation plate parallel to bottom.




























The sweet spot for top speed seems to be with the jack plate at 1.5" so next I may try moving the motor up a hole or two. I was getting 33mph loaded with two GROWN men and an 8 year old boy. There's no info out there about running this boat with a jack plate to compare with but IMO the 5 degree reverse wedge and SWW3 14 pitch prop is the ticket.


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## BBKing (May 22, 2010)

You installed the wedges upside down? Why?


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## jlo86cj (Dec 22, 2011)

BBKing said:


> You installed the wedges upside down? Why?


The transom had way to much wedge in it. The motor was level when I ran out of trim ram.


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## BBKing (May 22, 2010)

Really? From the pictures in looks like you have plenty of trim left; but, if it works for you.... Now you should try a anti-ventalation plate.


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## Rickey Bobby (Jul 1, 2009)

I wouldnt even waste my time moving the motor up. Not sure what your trying to achieve, she will already run in a puddle without the j/p. But hey, it does look cool.Good looking sled by the way.


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## jlo86cj (Dec 22, 2011)

I doubt I'll move it up any time soon. I imagine in rough water I'll want to get it as low as I can.

I am definitely gonna try a ventilation plate and when my funds recoup from the new lower unit and T&T rebuild I'll have Bob's put a low water pickup on. I have good water pressure so far, but the floating grass around here in the summer is thick and the LWP's handle it much better.


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## teamfirstcast (Aug 23, 2006)

There's so much conflicting info here not sure if I got it all straight?!? 1st observation/question: Why would you consider moving the motor UP when you cant raise the plate past 2? Also, when all the way up, your prop is running way above the water flow coming from the tunnel. You will never get on plane with it all the way up there anyway... i would consider moving the motor down a hole or even two so you can use more of the jack plates range. 

To your original question I see three issues (my opinion only, but comes from experience): 1) Start with motor jacked down - you need more water on take off 2) No need to trim all the way under, just put the cav plate just past level - you want a little bit of neg trim on take off, then trim up as she comes on plane. 3) You need a diff prop or some prop work with that 4 blade: Get lots of cup installed on those blades.

BTW, nice rig and Ive never even seen that model here in Texas (jealous!)


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## jlo86cj (Dec 22, 2011)

The SWW3 3-blade prop solved the problem. I can now get on plane with the jack plate fully elevated. The only reason I was considering moving the motor up was to see just how high it would run with the new prop.


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## Rickey Bobby (Jul 1, 2009)

Yeah, the 17t is a fun little boat. Mine will get into some hairy stuff without a j/p. That mini tower is sweet as hell.


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## jlo86cj (Dec 22, 2011)

They are awesome. The Hewes repacement (Tailfisher) had a nicer deck layout, but the tunnel looked smaller and it was heavier. I can't think of a better boat for where/how I fish, so I'll probably have it for a long while.


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## Flat's Hunter (Oct 18, 2007)

Looking at your pic the bottom of the skegg looks even with bottom of the boat. If so then there is no need to move higher.


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## Little Jimmy Cook (Oct 22, 2004)

*Pathfinder 17t*

I just purchased the same boat around a month ago. My boat has three blade prop, jack plate but no trim tabs. I am sure the more I use it the more comfortable I wil.
l get with it. It runs skinny, floats skinny and I am sure it will fish just as well as my Shallow Runner did . I rewired the boat and some trailer parts. The boat ran pretty good my first time out with it with the exception of a leaking live well that allowed a large amount of water to enter the hull.


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## Number_Five (Feb 14, 2012)

Curious to know where your motor is mounted as standard....hard to describe what I mean, but if you had no jack plate at all you would position your motor so that the cavitation plate would be even with the bottom of the boat, or up by an inch...can't remember.

But if you had your motor mounted too high with the jack plate in a neutral position, raising the jackplate would cause cavitation. Lets say the standard run position of the jackplate would be 2", or 1", then you would still have 4" of travel up. Not sure if that made any sense, it's been a long day.

Either way I'd put a larger cavitation plate on to inhibit some of what you're seeing.

Five


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## meterman (Jan 2, 2011)

had the same problem prop guy fig out that the 2 stoke 90 yami really did not need the vent holes welded up made a world of diff. 13 1/4 x 17 heavy cup 169 ranger ghost 4" bobs jp.


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