Troll valve

[Hunter]

Hello team.
I have a '78 38' with DD-671. My question is does anyone know how to go about adding a troll valve or troll mode to the twin disc transmission? Model SM-175. Or do any of you have that feature, maybe you could share some photos of what that looks like.

I can't troll for salmon the boat won't go slow enough. I know first world problems.

Appreciate any help

-Hunter

[Brian Haydin]

I use drift socks to slow the boat down.  I only have a 23', so my issue is much less dramatic than yours, but it's an effective solution that a lot of my charter friends use.  I've also used it with my brother's 42' Avanti, and been able to get the speeds down to just over 2 mph.  Amish outfitters make really nice ones, but might not be large enough for your boat.  

Regardless, this is a much cheaper solution (~150.00).  It has the added benefit of stabilizing the troll.

Hope that helps.

[Anthony Buhay]

Would love to see a photo of a 23 footer, Should share if ya have it.

[Kevin McIntosh]

Hunter ... you have Twin Disc MG-506 R & L gears ... SM-175 is the # for your Service Manual ...

I have the trolling option on my MG-506 R(ight, aka Stbd) gear ... that side also has an external Purolator cannister filter (TYPE P-192-04-3) in the gear oil cooling circuit (the gear oil for both of my gears is cooled by a vertical, tubular, inboard, closed-side cooling extension to the underside of my San Juan Engineering [now Seakamp] heat exchangers) ... whereas the Port side does not have the cannister filter in-line ... I've never tried my trolling valve out yet.  What's happening is you're inducing slipping of the clutch plates in the equipped gear to result in a slowing down of the boat ... that's why Twin Disc specified the addition of the the external cannister filter.

I like Brian's thought of the drift socks for simplicity and multi-tasking capability (aka sea-anchors, they can also pull the bow into the weather if you lose power and will slow your drift into hazardous shallows, ect.) if you're by your lonesome and headed in straight lines most of the time ... but my experience at the mouth of the South Arm of the Fraser River in Richmond (part of Greater Vancouver), B.C., Canada tells me that with a high concentration of smaller fishing boats all orbiting around in the shallows off the mouth of the river, commercial traffic literally barging through more or less constantly, and, multiple lines out on downriggers, a cluster-f*&k would quickly ensue ...

Seems to me if one of your gears is not already equipped with the trolling valve (and you really gotta' have it), you may be better off to wait 'til one of your gears sh*ts the bed and then swap it out for a good used or rebuilt unit that has that feature ... unless you like throwing $ at stuff ...

Kevin Mc

[Hunter]

Kevin! Brilliant summary of my trolling experience, "barging through more or less constantly, and, multiple lines out on downriggers, a cluster-f*&k would quickly ensue ... ".

You might be right, about replacement but the gears are the most reliable and only thing in the engine compartment that don't leak oil, so it may be a while. I am still curious and might like to try to set one up. Could you email me photos of the troll valve, the gear, and the filter set up when you get time? Is there a part number for the troll valve part that's attached to the gear box?

hwie...@gmail.com

-Hunter

[Tod duBois]

So I prefer grocery shopping in my 1978 Corvette, why? because with the T tops off I can fill it with groceries and frozen fish. It is way better than using the mini-van since with the minivan the food and bags fall over in the back on the ride home and that never happens with the Vette stuffed uptight. 

[Kevin McIntosh]

Hunter ... I'll see what I can do from file photos ... right now I'm in 14-day quarantine, so, cannot visit yon boat (it's on-the-hard, so, once I am able to visit her [provided I'm not DOA], I will be busy as f*&k prepping the running gear & bottom for re-launch back into yon water) ... I've never identified any seperate, bolt-on component(s) that I took to be associated with the trolling valve (nor did I have any reason to look for / at that), thus, nor have I seen any numbers stamped in or on any plate ... do you have the Twin Disc engineering (BOM) diagrams for the gears?  Or just the SM-175?

They may or may not shed any light on what's involved.

Tod ... WTF?  R u troll'ing us?  Ha-ha ... FFF

[Hunter]

Kevin,
I have looked in the manual which does have some gorgeous drawings. But they don't show the troll valve. One faintly shows a spot for a mystery, "Optional item" but no details or numbers.

[Kevin McIntosh]

Hunter ... look at these items I have attached ...

 ... my Stbd. gear is SPEC. NO. (BOM) 34696 ... it is the gear with the Trolling Valve ...

 ... I do not see anything like an "Optional item" (can you scan and Fwd your drawing / with this reference please?) in the drawing 'Xa7022-1_Install Drawing.pdf', however, I do note the non-Standard part 'T122' ... which is described in Sheet 2 of 2 of (BOM) '34696.pdf'.

Also, note the information regarding ' ... made of "sintered" bronze (clutch plates) which contain iron ... ' in 'OilSampleIssues.pdf' ...

As to photos of these components, I only have access to my file photos right now and what I've uploaded is all I've got at the moment.

Kevin Mc