Best place for thru-hulls

[imjustinbraun]

I have a pair of transducers I need to install (Raymarine water temp/speed/depth). Can anyone recommend the best place for them? Looking to stay out of way of getting clipped by the trailer, somewhat easy to access in case I need to clean them, and will stay in the water when I'm on plane.

[Russ]

I have a pair of transducers I need to install (Raymarine water temp/speed/depth). Can anyone recommend the best place for them? Looking to stay out of way of getting clipped by the trailer, somewhat easy to access in case I need to clean them, and will stay in the water when I'm on plane.

My transducer is on the transom aft next to the rudders. (looking for a pic).

Others have mounted in a silicone bed inside the hull.

Speed?? Mine doesn't work. GPS has speed for me. Depth and water temp are what I have.

[imjustinbraun]

I bought the Raymarine i50/i60 kit that puts wind direction & speed on top of the mast, and then has 2 thru-hull transducers that will need holes drilled through the bottom. I'm asking for suggestions on where I should drill that hole. I want it to be towards the back so that they don't come out of the water while on plane but I also don't want to accidentally drill through the ballast tank or end up putting the depth transducer on too much of an angle.

For reference I bought this guy here:

[Starscream]

I bought the Raymarine i50/i60 kit that puts wind direction & speed on top of the mast, and then has 2 thru-hull transducers that will need holes drilled through the bottom. I'm asking for suggestions on where I should drill that hole. I want it to be towards the back so that they don't come out of the water while on plane but I also don't want to accidentally drill through the ballast tank or end up putting the depth transducer on too much of an angle.

For reference I bought this guy here:

It's a tough question. I have totally avoided doing anything that required me to drill a hole through the hull below the waterline.

The transducer would have to be fairly far back so that it would stay in the water when the boat is on a plane, and it would have to be as near to the centerline as possible to stay in the water while sailing. And, you have to avoid drilling the ballast tank. Once it's in, you should probably try not to beach the boat so that the transducer is supporting boat weight. Then, you have to make sure that the location you choose doesn't line up with any trailer bunk, or get in the way of the MacBump slide-fix.

So I can't help really with telling you where to do it, but please think about trailer, ballast tank, beaching, heeling angles, and motoring angles.

[Jimmyt]

Best place for thru-hulls? In somebody else's boat...

Starscream pretty much covered it, if you're going to do it, though. I glued a block to my transom and mounted my down imaging transducer to it. Had to fiddle with it a bit to get good readings, but works pretty good now.

Joking aside, all of my "real sailboat" buddies have numerous thru-hulls, so you will be fine if you install them properly, and follow Starscream's advice on the trailering and beaching concerns.

I'd put them under the aft berth, toward the transom end, but wherever they're easiest to access. I'd put one on either side, offsetting them a bit from centerline to try and get out of the disturbance of your swing keel and trunk.

And please post pics of you're install. We're rooting for you.

[OverEasy]

Hi ImJustinBraun!

On the Mac26X there are ballast tanks in the aft berth floor so that’s not a good location as it goes nearly to the stern.

There is access to the hull from within the aft dinette bench once you lift out the fiberglass storage bin and if you were to mount it along center as far aft as you can easily access it will remain in the water while you are on plane when motoring AND while heeled over when sailing.

Personally I’d suggest avoiding making a thru hull penetration below the waterline for just about anything. The hulls on our Mac26Xs aren’t known for thickness or exceptional rigidity. Highly suggest you at least try bedding the transducer in silicone or making a liquid gel box to place it in rather than drilling thru the hull and hoping it holds up over time.

IF You decide to go ahead anyway and drill thru your hull I’d suggest considering when placing a thru hull what might possibly come into contact with it or the flange such as when getting on/off the trailer normally and under odd or unusual conditions. ( Plan for the worst and hope for the best… ). Also remember that if one deliberately or accidentally runs aground that there will inevitably be uneven hull loading which mayaffect the region of your thru hull location below the waterline.

But it’s your boat and your rules.

Best Regards
Over Easy

PS: Here are some sectional views from the Mac26X drawings showing the water ballast.
The “ice chest” is the aft dinette bench.

[Jimmyt]

OverEasy is correct. Looks like your spot is going to be around or between stations 2 and 3. Either side of the trunk, offset to get in clean flow is probably a good idea still.

[imjustinbraun]

Thanks for the suggestion @overeasy! I think right under the dinette bench as close to the centerline as possible is a fantastic spot. My is going in for some coppercoat bottom paint next week so I'm going to try and get it done today or tomorrow. I'll grab some pics as I do this and post a write-up in here as I go along.

[imjustinbraun]

So update. It turns out that close to the centerline underneath the dinette bench is NOT a good place for a thru-hull as there's still a small sliver of ballast tank there. I think what I'm going to do is try to superglue some small wood blocks between that gap to give that space some compression strength, then over tighten the thru-hull transducers to keep the entire thing under pressure even when the outer hull flexes in relation to the inner hull. Though I'm open to suggestions on what to do with this one...

[Jimmyt]

Is the top piece your hull liner or ballast tank? Drawings don't show ballast tank there. If it is ballast tank, it makes no sense why they put the tubes in. If it is ballast tank, I would glass in a sleeve, install your sensors, and never look back. This is not a problem.

Just for chuckles, suggest you close the ballast vent, put a leaf blower on your ballast valve (not sealed tight) and see if you feel air coming out of the annular space.

[imjustinbraun]

Is the top piece your hull liner or ballast tank? Drawings don't show ballast tank there. If it is ballast tank, it makes no sense why they put the tubes in. If it is ballast tank, I would glass in a sleeve, install your sensors, and never look back. This is not a problem.

Just for chuckles, suggest you close the ballast vent, put a leaf blower on your ballast valve (not sealed tight) and see if you feel air coming out of the annular space.

It's definitely the ballast tank. I poured a bottle of water into the ballast vent and water came right through that gap I drilled.

[Jimmyt]

Looks like you have good access from the top. You could over-size the top hole and glass the sleeve in from the top. Hard for me to understand the design strategy, but, whatever. It is what it is.

Just a bit more work, but still no big deal.

[imjustinbraun]

Looks like you have good access from the top. You could over-size the top hole and glass the sleeve in from the top. Hard for me to understand the design strategy, but, whatever. It is what it is.

Just a bit more work, but still no big deal.

I'm trying to decide whether it's best to oversize the hole then glass in a sleeve...

...or just keep the whole thing under compression by coating some wood shims in superglue and wedging them in that gap, then over tightening the thru-hulls, then burying the whole setup in silicone.

My worry with trying to glass in a sleeve is that the inner hull might move in relation to the outer hull and stress out the sleeve over time. If it breaks I'll just have a massive leak with no chance to fix it before the boat sinks. I feel like this is less likely to happen if I shim and seal.

Thoughts?

Lastly, and this might be a stupid question given what just happened but I have to ask... Does anyone have any suggestions where I should put the next through-hull?

[Jimmyt]

If it's done correctly, glassing it in should be fine. Glassing from the top will maintain hull integrity. If the top joint broke, you'd get a ballast leak into the boat, but it wouldn't sink if the ballast valve was closed. I doubt it would fail catastrophically. More likely, you would get a crack that would weep water.

However, your idea of putting a spacer in between the two tank walls, then sealing the top and bottom pieces of the transducer when you mount it should work, also. The two surfaces can't be allowed to flex inward toward each other to maintain water-tightness. But, if you did get a leak, it would probably be manageable.

You're in it now, and you know what you're up against. Might as well put the next transducer where you want it. You have to develop a method for the first hole. It appears that the drawings aren't good enough to depend on, and nobody who is currently on the forum knows exactly how the X hull is constructed in that area.

If you go the hull spacer route, I would use HDPE, fiberglass board, or some other material bedded in 3M Adhesive sealant 5200; in lieu of wood, superglue, and silicone. Use 4200 when you install the transducer, though (so you can remove it).

[imjustinbraun]

Bah I wish I'd read that suggestion before I already put the wooden shims in. I ended up going for treated wood. It turned out surprisingly good. I think you're right on the second thru-hull. Now that I know this won't be an issue, I'm just going to do the next one right next to it. Also only gives me one place to look for when trying to spot trouble.