Best place for thru-hulls

[Jimmyt]

I'm sure it will be fine the way you did it.

For giggles, this is what I was talking about regarding glassing it from the top.

[imjustinbraun]

Yeah on second thought that glass sleeve idea would have probably been a really good one. I could have just made a 1ft diameter hole then put both of the the thru-hulls into just the outer hull. Oh well. I'm pretty sure the way I did it is perfectly fine. While inspecting further I also realized that if I would have located those thru-hulls towards the way back of the hiding spot for the swing keel instead of towards the front of the "ice box" I might not have had this problem at all. Alls well that ends well. The thru-hulls are installed and the boat goes in to have the hull stripped down to the gelcoat and have coppercoat applied tomorrow. Signing off for now. Night!!

[OverEasy]

Hi ImJustinBraum,

OMG!
That was entirely unexpected!!!
AND confusing!

So as was said by others “What’s the point of the ballast transfer tubes?”
What you have discovered is a genuine surprise and I can only wonder if there are variations in the ballast tank constructions for different years of manufacture.

What year of manufacture is your Mac26X?
(Not to in anyway question that you have found what you found and that you have worked to a solution to deal with it.)
But early Mac26X production had a different ballast tank vent location vs. latter units. The early units have a fiberglass step at the cabin companionway that also houses the ballast tank vent. Later Mac26X have the ballast tank vent forward under the V Berth.

The factory cross section diagrams available in the resources section brochures for different years have the same cross section image.
I’m so sorry that what you discovered was not what had been anticipated.
The upside from all that you have discovered is that your boat and others have a “double hull” in that region that was previously unknown until now.

We have had our transducer mounted in a bed of sticky wax box at the same location all last year on the interior surface.
Others have used the same non-penetrating approach with a bed of silicone sealant.
We have used the sonar with and without ballast water without any noticeable change in depth readout.
Would have thought that if there was a gap such as you have incurred the transducer would have gone off-line when the ballast was empty such as when we first launch from the trailer. I can only assume that if our boat has the same arrangement is that these layers are in direct contact or had an inter layer filler applied. (The only reason we were planning to do anything with our current transducer arrangement is to enlarge the existing narrow box in an attempt to be able to expand the “side scan” capabilities of the Garmin transducer.)

Best Regards
Over Easy

[Jimmyt]

One other small comment. Usually it's best not to line up sensors in direction of flow, when mounting them near each other (if I understand your photo). You want to have reasonably undisturbed flow over them, so you don't mount them behind strakes, centerboard trunks, or other flow disrupting features. Your other transducer appears to be low profile, so you may be fine.

Like I said, for future reference.

[imjustinbraun]

So as was said by others “What’s the point of the ballast transfer tubes?”

So I think that the tubes are there to ensure that water can easily flow into the forward part of the ballast tank. They probably also offer a lot of structural rigidity. There really isn't a whole lot of space in that "double hull" section at all and I can't imagine there being a lot of room for water to flow freely from back to front without it.

What year of manufacture is your Mac26X?
(Not to in anyway question that you have found what you found and that you have worked to a solution to deal with it.)
But early Mac26X production had a different ballast tank vent location vs. latter units. The early units have a fiberglass step at the cabin companionway that also houses the ballast tank vent. Later Mac26X have the ballast tank vent forward under the V Berth.

Not sure what year of manufacture but it's a 1999 model year. I do have a fiberglass step at the companionway but it's just a little doghouse with a small amount of storage (I sometimes use it for water bottles). The ballast tank vent is at the forward part of the V-Berth just like most others. I can get a picture of it if that is of interest.

One other small comment. Usually it's best not to line up sensors in direction of flow, when mounting them near each other (if I understand your photo). You want to have reasonably undisturbed flow over them, so you don't mount them behind strakes, centerboard trunks, or other flow disrupting features. Your other transducer appears to be low profile, so you may be fine.

Makes total sense. So the forward transducer is the paddlewheel for the water speed sensor and absolutely needs undisturbed flow. The second one is the depth sounder and water temp sensor which is quite a bit more flow agnostic. I wanted the depth sounder to be as close to the centerline as possible which was why I felt that locating it behind the paddlewheel wouldn't be much of an issue.

[OverEasy]

His ImJustinBraun!

1999 must have been a transitional year for the Mac26X production changes.
MacGregor was one for continual product/production improvements while not wasting components that were already fabricated and still usable. The earlier Mac26X had the fiberglass step & vent while by 2000 that had been replaced by the swing up step and the V Berth vent arrangement. The change in vent location was purportedly to improve the water ballast flooding and minimize the potential for an ‘air bubble’ in the forward portion of the ballast tank (making sloshy noises).

I’m glad you were able to get the double hull aspect solved without too much trouble.
(That was very unexpected. )

Someday someone ought to write a definitive design iteration technical book on the MacGregor series of boats with dimensional drawings for the multiple thousands of MacGregor owners out in the wild

Best Regards
Over Easy

[Outdoor-Michel]

Hello everyone,

I also installed a log transducer and drilled through the ballast tank.

I sighted and stabilized the gap with glass fiber filler V11 from VOSS Chemie.

Here are some pictures.

Greetings from Germany,

Michael

[Jimmyt]

Greetings Michael! Very nice job on the transducer install! The workmanship is excellent.

Welcome to the forum! Looking forward to more of your posts!

Jim

[Outdoor-Michel]

Hello Jim,

Thanks for the feedback. I'll see what I can do

In the last 4 years I have made many modifications.

Michael

[OverEasy]

Hi Outdoor-Michel!

Great post on your mod to mount your transducer!
You and ImJustinBraum have both done a great service to our forum community with regard to the implementation of your thru-hull transducers.
If I might ask, What year is your Mac26X?

Best Regards
Over Easy

[Outdoor-Michel]

Hello OverEasy,

thanks very much.

The Mac26x is from 2002.

Outdoor-Michel

[OverEasy]

Hi All

Given what ImJustinBraum and Outdoor-Michel have shown with their 1999 and 2002 Mac26X “through hull” transducer installations I became curious as we have a Mac26X 2001 hull.
Our initial internally surface mounted transducer ( non-penetrating) location was in the same general area (give or take an inch or so) in a bed of sticky wax. So how did ours work with or without water in the ballast tank? Hmmmmm?

We’ll I did some further research and reading trying to find out.
What I found was that several others have used the interior non-penetrating transducer mounting approach as well with a variety of fixatives such as Silicone seal, 5200, wax, mineral oil saturated foam, water filled enclosures and petroleum jelly! All have had good results with never a mention of needing to have the water ballast tank filled.

I did find a very good copy of the original factory MacGregor Mac26X cross section for this area. (Not perfect but better than what I had before.) This better copy definitely shows a gap between the inner surface of the ballast tank and the actual hull surface!





So again I learn something new about our interesting and fascinating multipurpose trailer/sailer/cruiser pocket yacht!

Now the question arises as to “How have I been able to get such good sonar images and depth readings when the ballast tank has definitely been empty and there should have been an air gap between the ballast liner and the hull which should have been more than sufficient to have messed up ant reading at all?”

Now I did notice that I wasn’t getting any valid “side-scan” images from our Garmin system which is why I had deinstalled our original setup and am in the process of enlarging it with the hope to improve the ‘angular side window’ of the transducer while still keeping an interior non-penetrating transducer mounting…. I assume it is going to possibly require a bit of trial experimentation, but at least now I know that this gap exists in this region of our Mac26X hull/tank structure.

So this is sort of what we had initially:


And this is what we have been planning to do to improve the side-scan capability:


We are also proposing changing from bedding the transducer in sticky wax to submerging it in mineral oil saturated open cell foam and sealing the new housing to prevent any potential for fluid leakage.(The sticky wax appears to have separated from the transducer either during transit from SC to Lake Champlain VT or when we were slung out to have our bottom anti fouling redone.)

Regardless, the excellent postings by ImJustinBraum and Outdoor-Michel have added to our collective knowledge of of forum!
Thank you both!

Best Regards
Over Easy

[Russ]

I'm not familiar with "side scan" transducers.

I've installed several transducers simply by mashing them into a bed of silicone caulk making sure to avoid air bubbles and voids.
It's worked flawlessly on several boats I've done this on.

They do make kits to bed them in mineral oil.

I prefer the silicone as it's inexpensive and can be removed with a razor blade if it doesn't work.

Also, I've read to test location by placing the transducer in a ziploc bag full of water and place it against the hull. Not easy to test while on the trailer though.

This video shows how to do it. However, I prefer the silicone caulk as a medium.

[OverEasy]

Hi Russ!

Yes, I think that is a good idea!
I think that I’ll get the new box made up and fitted but not sealed in place and then do the large water bag to give it a test to see what we can see,

Garmin and others make a transducer that not only looks straight down but also out to the sides.

Normal sonar gives you an average trace of the sea bottom you have already traveled over more or less directly under the transducer.
This varies a bit by depth getting wider as depth increases but is still pretty much limited to averaging a straight downward facing cone of about 15 to 30 degrees.
Nothing much to port or starboard.

The side scan systems, under ideal circumstances, looks to each side in a somewhat linear ‘barrel’ of about 170 degrees.
This can provide a better idea o the actual bottom surface conditions and features/obstructions.
It can help you find and maintain a centered position when transiting a dredged channel for example without “discovering” the edges the “hard” way.
The system also provides a limited “look forward” capability of about 15 to 30 degrees with image content to help one “see” potential obstructions and take appropriate avoidance action.
The ‘3D’ image of bottom contour and features (sunken trees, pipes, boats , etc ) can also help when fishing or anchoring.
(Who wants to drop anchor into the branches of a sunken tree if that could be avoided? )

This is a feature that our initial installation didn’t allow enough ‘view angle’ to utilize.
The initial install did great at looking straight down but wasn’t able to look to the sides.

Another potential aspect is in corporation of a manual capability to rotate the transducer about a vertical axis.
5his would have the benefit of being able to increase the “look forward” capability substantially if the need arose ( say when approaching areas subject to dynamic shoaling that charts can’t keep current with or for carefully approaching a cove that doesn’t even list on the chart).

From our exploration of the estuaries around Beaufort SC the side look capability would be a nice feature as the water flow is continually reshaping the natural channels. Often quite abruptly!

It would also be kinda neat to “see” more of what might exist ,below the surface’!

Best Regards
Over Easy
fudt

General idea of what side scan ca provide:

[KonstantinAtHouston]

Thanks, imjustinbraun, and everyone. It was interesting and informative reading.

I think it should be considered established (cast in granite ...or was it bronze?) that central area in the cabin of M26X (red lines) is, against the impression and popular belief, is not attached to the outer hull directly, but has a thin channel connecting it to the water ballast tank. So think twelve times before drilling. Luckily, imjustinbraun also provided us with reliable way of plugging the drilled holes.

Now, who is willing to drill in other areas? Green, blue, yellow? Anyone?