I have a new manitou tritoon depth finder only works at slow speeds

SOURCE: depth finder problem

Try adjusting the trim or get the boats nose up even to the point of porpoise (I think thats how you spell it) if the signal improves with the nose up you may need to lower the transducer more than the manufacturer recommends. the slight looking foward will also help. My current sounder works pretty well up to about 25kn

SOURCE: navman 4150 fishfinder

Depth: Could be for a number of reasons, too deep for the sounder - check the manual for it's max depth. Dirty water, sounder unable to penetrate through to the bottom. Weed or other debris covering the transducer. Transducer on a swing mount & being pushed out of alignment then dropping back in once stopped.

Speed: Is the speed readout controlled by a GPS or paddlewheel? If it's GPS, check the power connection of the sounder, may be loose which would also cause the depth to 'drop out'. If it's paddlewheel, you're down to bad connections or faulty unit.

SOURCE: navman 4500 fish finder w/transom mount transducer

I finally got an email reply from Navman. If the unit is less than two years old (mine is not) they will repair it. If it is over two years old, or if you can't prove that it is less than two years old, you can ship it to them and they will repair it for the low, low price of 355 US dollars.

Pretty nice of them since it appears these units are highly problematic isn't it? I am wondering if they guarantee their fix, or just have you on the hook for another 355 dollars later.

Good Luck Everyone,

Walt

SOURCE: installing an old used lowrance fish finder

I don't think your old fish finder is the LMS-332C GPS Receiver listed above in the description. You don't need the speed wheel for the fish finder to function just the transducer and transducer mount. You should mount that on the back of the boat towards the center but not too close to the motor and not too close to the side of the board. Don't let it hand below the level of the boat. That should keep it from getting hit by the trailer or dragging on the bottom. Try to make it as level as possible. The green and white wires may be for the speed wheel but i'd need a model number for clarification. Hope this helps.

SOURCE: No depth reading while on plane.

Depending on your transducer type, you may have a liquid filled type that simply needs refilling. If this is the case check for leaks and get it redone. If not it could be transducer placement or cavitation under the hull.