Re: transducer mounting
Bill,<br /><br />I have installed a wad of them. So here you go:<br /><br />First off I presume you bought the 525ST-MSD tranducer. I don't have one here at the moment but it would look just like the used one shown in the picture below:<br />
<br /><br />The fairing block you have should match the top side of the transducer body and is probably made of a blue plastic that looks and feels a lot like starboard. That stuff cuts just like wood, and not a very tough wood at that - about like cutting through poplar or something. At any rate it can be worked very easily with normal wood working tools. It will not melt and gum up cutting tools, that is my point.<br /><br />OK, first things first. You need to get the boat itself level. Once again I will make an assumption, and that is that your boat is on a trailer. Get the boat level in the Port/Starboard direction first. Just take a level and place it across the deck and then get out there with your jack and jack stand and jack up the trailer as you need to in order to get the deck level. I find that just putting a chunk of 2x6 under one of the sets of tires tends to work well, but you do whatever you have to in order to get it level and hold it there.<br /><br />Once that is done you have to get the boat into approximately its normal running angle. By that I mean that you need to use the trailer jack up front to raise the front of the trailer so that the deck of the boat is at approximately the same angle it would be if you were up on plane at your normal running speed in dead calm water. For most boats this would be a slightly nose high angle, but not really all that drastic. You have to guestimate this one unless you have the ability to take the boat out for a quick spin. If you can put it in the water do so and take someone with you as well as a long level. With someone else running the boat lay the level on the deck pointing fore/aft and then see how high you have to lift the rear end of the level to make it read level. Then get home and duplicate that angle in your driveway (with the boat already leveled in the Port/Starboard direction). Now you're ready to begin actual instillation.<br /><br />Where do you plan to drill the hole? <br /><br />Look very very closley at the bottom of your hull forward of where you would like to mount the transducer. If there are any fittings, thru hulls, or strakes ahead of the point you choose then choose another place to mount it. At the same time look aft of the point and make sure there is nothing (like a roller) on the trailer behind the point you've chosen. Remember, the boat will go on the trailer the same way every time, within an inch or so, and so if its safe when you do the mounting it will stay safe when loading or launching. There is absolutly no reason on earth that a thru hull can not be used on a trailered boat - I just wanted to do away with that old wife's tale once and for all. Its pure hogwash.<br /><br />OK, now you've got a place in mind on the outside of the boat. Measure from the chosen point to the transom and to each side of the boat. Assume your transom to be 2" thick. Now go inside the boat and see if you have access to the same spot from the inside. Good luck on this one. Measure and measure and measure and measure and measure. If you firmly believe that you've got the right spot break out the drill.<br /><br />From the
INSIDE of the boat drill a quarter inch hole through the hull. Drill it straight up and down not at a 90 degree angle to the hull itself, even if you've decided to mount the transducer right on the center line - which is just fine, and in fact often the best place to mount a thru-hull.<br /><br />Now, with a pilot hole drilled from the inside of the boat get back under the boat and see where it came out. If you have any sort of luck at all it will be within a couple of inches of where you wanted it. If it is where you want it break out the hole saw and burn a hole in the bottom. If you missed its an easy task to patch the small hole with an epoxy/high density filer mix. Do not drill the hole to a much larger size than the stem. If the stem is 2" then drill a 2 1/8" hole, no larger. As for myself I prefer to drill the hold the same size as the stem and then enlarge it slightly with a rasp, but going slightly larger is fine.<br /><br />Once you have the hole drilled you need to do this; take a very good hard look at the plug that comes out of the hole saw. See if there is any sort of coreing material or if its pure glass. Let me give you a hint, there is almost no chance at all that there will be any coreing - despite the nonsense you see all the time on the internet there are actually almost no boats of trailerable size that have coreing anywhere, let alone in the bottom. At any rate if your's is one of those extremely rare boats that has any coreing you have to deal with it.<br /><br />If it has coreing break out your pocket knife (or dremel tool) and get under the boat. Dig out the coreing material back from the hole by about a quarter inch. Then go to your local West Marine, Boater's World, Boat US, or whatever is handy and pick up a quart of West System epoxy (and hardner) along with a can of their #404 High Density filler. Take it home and mix up about a half a cup of the stuff. Jump right under the boat and wet out (just take a throw-away paint brush and slobber some, but not much, of the juice in there) the cavity you dug out with your knife or dremel tool and then go back to your mixed pot and put in enough of the high density filler to make the stuff about the consistancy of peanut butter. Now get back under the boat and take that blob of peanut butter looking stuff and force it into the dug out chamber all the way around. It will bond nicely because you wetted the surfaces out completely with raw epoxy/hardner mix beforehand. There, you have just sealed off the coreing and it took you all of 15 minutes - problem solved forever.<br /><br />Back to the real work.<br /><br />This is the smart part. If you don't already have one head for Sears and pick up an adjustable bevel. This a a tool that has a handel with an adjustable blade, that can be locked at any angle that will run you around $5. It will be with the woodworking tools. Take it and get under the boat with a short level (about 9") and set it at the angle of the hull directly at the hole you drilled. Put the level on the bottom of the handel part of the adjustable bevel with the blade up against the hull. Level it up and lock the blade. <br /><br />Now, take the bevel back to your saw and use it to set the angle necessary for cutting the fairing block. Cut the fairing block basically in half, at the angle of the bevel. You need both the top and bottom half of the fairing block after the cut. The bottom half will be used outside of the hull to level up the transducer, the top half will be used inside the hull to give a flat surface that is at 90 degrees to the stem to allow the Transducer's nut to seat to a flat surface. The square flat top of the fairing block that is on there to act as a saw guide will be facing up and will provide a flat level surface, at a 90 degree angle to the stem, for tightening the nut to.<br /><br />Next step [This is a step that you probably have never heard of before but its what is going to make your instillation work better than anyone elses]: Take the bottom half of the fairing block and get back under the hull. Take a sanding block with 36 grit paper on it with you too. Hold the fairing block up to the hull and check it for level in both the Port/Starboard and Fore/Aft directions. Using that block and sandpaper I want you to spend the next hour getting that transducer perfectly level. Don't worry about the other half of the fairing block, its not nearly so important, but the half on the outside has to be exactly correct (remember, you already have the boat itself level from side to side and in its normal running attitude). I said this will take you an hour - in truth it will take you maybe 15 minutes, but it will make all the difference in the world in performance.<br /><br />When the fairing block is as good a fit as possible go drink a beer or something and get the notion that you need an anchoring screw or bolt out of your head. Once you've done that come back to the boat with your sealer and 4 stainless steel flat washers of either 1/4" or 3/8" size (they sell them at both Lowe's and Home Depot). You are going to need to have someone inside the boat to help you - so go get them too.<br /><br />A wise person will do all of this next set of steps as a trial fit first without sealer and will check the bottom face of the transducer for level in both directions before they ever break out the tube of sealer:<br /><br />Inside of the boat take the top half of the fairing block and mark where it is going to contact the inside of the hull. Lay down a full coat of your sealer (you do not need, and I do not recommend 5200 for this, 4200 will work just fine and is preferable). Place the top side of the fairing block into the sealer. Then, from the bottom thread the transudcer cable through the bottom half of the fairing block and then up through the hole in the bottom. Have your helper grab the cable and pull it into the boat. When its all in there except the last couple of feet stop and put your sealer on the top half of the fairing block. Also coat the top of the transducer itself with sealer. Do not put sealer on the stem, just up close to the stem. Now, slide the fairing block half up to the hull and press it in place (the sealer will hold it) and aline it exactly straight pointing forward. <br /><br />Now the part you didnt' expect. Take those 4 stainless steel washers and lay them into the sealer that you put all over the top of the transducer. Put two of them together, stacked, one each side of the heel of the transducer. They are going to act as spacers to hold the rear of the transducer just a couple of sixteenths of an inch farther away from the hull than the front is. Place them inboard of the edge of the transducer by about a quarter inch and about a quarter inch from the aft end of the transducer, two on each side. Now push the transducer up with its stem going through the hole. Your helper, on the inside, will gentelly pull the cable up as you do this and then will put the big nut on - by hand. You will stay under the boat to make sure the transducer stays dead straight pointing forward. Tell your helper to tighten down that nut - firmly by hand, until they see some of the sealer squeezing out from the sides of the upper half of the fairing block - all the way around. I want that nut firmly tight, but not tightened down with a wrench of any kind at all. <br /><br />Now stop.<br /><br />I want you to let it all set for a day and a half. After a day and a half you go out there with the channel locks and tighten down that big nut. Get it firmly tight, but don't try to see how hard you can crank on those channel locks. What you have done here is allow the sealer to seal and the nut to hold. What you have avoided is squeezing all of the sealer out of the two joints under the boat (hull to fairing block is 1 and then fairing block to transducer is 2. You also have a complete seal between the top half of the fairing block and the insider of the hull.<br /><br />There, that's it. This whole process takes a couple of hours. Its not at all difficult.<br /><br />Got any questions?<br /><br />Thom
