I have a 87 Mac 25. Where she sits on the trailer "dimples" have formed. This may be nothing, however I think the previous owner my have changed somthing to cause this. If you can help please let me know. I maybe able to send you a pitcher is necessary. Thanks
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Bunk boards too stiff ....maybe?
I think there is a possibility that the previous owner may have replaced the bunk boards and have them adjusted with too much tension. You may have to elongate the holes on one end of the boards to allow the center to sag a bit and conform to the shape of the hull. Anyway, that's my two cents worth for what think I'd do.
I think there is a possibility that the previous owner may have replaced the bunk boards and have them adjusted with too much tension. You may have to elongate the holes on one end of the boards to allow the center to sag a bit and conform to the shape of the hull. Anyway, that's my two cents worth for what think I'd do.
Bunk boards weak
Fiberglass was pushed in on starboard by the trailer with my V222. Then I noticed most of the older ones I saw were the same way. I concluded the hull must have a bulkhead supporting the port bow and is weaker on stb. Finally I realized the bunkboards were so rotted under their fabric that the hull wasn't being supported by the bended board; it was pretty much just sitting on the two points where the trailer mounts were. The stb bow was the weakest point and was severely dimpled in. I bought new (PT pine) boards, cut them 6" longer, and beveled the forward edge a little. Wow, what a difference! Now the whole board spreads support along the hull evenly. This is a common problem with older Macs trailers, and may be yours. How old are your bunkboards? They may be either weak or so curved by now that they have lost the stiffness necessary to press the hull along their whole length.
Fiberglass was pushed in on starboard by the trailer with my V222. Then I noticed most of the older ones I saw were the same way. I concluded the hull must have a bulkhead supporting the port bow and is weaker on stb. Finally I realized the bunkboards were so rotted under their fabric that the hull wasn't being supported by the bended board; it was pretty much just sitting on the two points where the trailer mounts were. The stb bow was the weakest point and was severely dimpled in. I bought new (PT pine) boards, cut them 6" longer, and beveled the forward edge a little. Wow, what a difference! Now the whole board spreads support along the hull evenly. This is a common problem with older Macs trailers, and may be yours. How old are your bunkboards? They may be either weak or so curved by now that they have lost the stiffness necessary to press the hull along their whole length.
beveled the forward edge
I have the same problem with my 83 Mac 22. I was thinking about replacing the bunks with a wider board, like a 2x8. Tell me a little more about the beveled front edge.. also you said you "cut the boards 6" longer", is that 6" longer on each end,for a total of 12" per board? Any change in launching and recovering? Tom
I have the same problem with my 83 Mac 22. I was thinking about replacing the bunks with a wider board, like a 2x8. Tell me a little more about the beveled front edge.. also you said you "cut the boards 6" longer", is that 6" longer on each end,for a total of 12" per board? Any change in launching and recovering? Tom
bunk board alterations
Hi Tom, I may have added more like a foot. The board is 6"x2"x11feet, with 18" in front of the forward stand and 6" past the rear stand. That carries the board forward to where it barely contacts the hull. (I extended the front because they ended right at the support where it dimples; I wanted to spread that stress point further forward.) It worked out great, despite my dithering about it. And, since the board can't twist to follow the v-shape, the hull touches the board's inside corner at the bow. I beveled the inside top corner off a little at the bow to soften that square edge. That inside edge goes from 1-1/2" down to about 1/2" in the last foot. The angled surface fits the vee a little nicer; just do what looks right! I'll take a picture tomorrow, but the fabric hides the bevel. Covered it with bunkboard fabric and aluminum tacks. I think 8" is too wide; fabric is usually 12" wide so it wouldn't wrap around the board. Plus the vee at the bow can't be changed too much, and the bend is about right for the hull curve. No difference at all in the boat's position at rest or launching, just no dimple. The main thing is the bunks need enough stiffness to spread the weight along their length, and need to be replaced every ten years maybe? John s/v Lyra '77 V22 or is it a Mac22?
Hi Tom, I may have added more like a foot. The board is 6"x2"x11feet, with 18" in front of the forward stand and 6" past the rear stand. That carries the board forward to where it barely contacts the hull. (I extended the front because they ended right at the support where it dimples; I wanted to spread that stress point further forward.) It worked out great, despite my dithering about it. And, since the board can't twist to follow the v-shape, the hull touches the board's inside corner at the bow. I beveled the inside top corner off a little at the bow to soften that square edge. That inside edge goes from 1-1/2" down to about 1/2" in the last foot. The angled surface fits the vee a little nicer; just do what looks right! I'll take a picture tomorrow, but the fabric hides the bevel. Covered it with bunkboard fabric and aluminum tacks. I think 8" is too wide; fabric is usually 12" wide so it wouldn't wrap around the board. Plus the vee at the bow can't be changed too much, and the bend is about right for the hull curve. No difference at all in the boat's position at rest or launching, just no dimple. The main thing is the bunks need enough stiffness to spread the weight along their length, and need to be replaced every ten years maybe? John s/v Lyra '77 V22 or is it a Mac22?
Dimples
I am new at sailing (about a year) and have owned a 1982 Mac 25 for about 8 months. When I trailered my 25 had a very large indention ( bigger than a dimple) on the bottom starboard just a little aft. Somewhere I read that, when you put your boat back in the water, you should wait for about a week to make your final adjusts to your shrouds and fore and back stays until the bottom smooths out? I can't find it again but it gave me the indication that a warped bottom while on the traileris normal. I am a little confused as to where my bunk boards are too ridged or too weak. I am guessing too ridged from the way the bottom looked. It is not a big deal just now as I have it in a slip but am going to check with the Macgregor Co. for their response. Another subject and concern is the thickness of the hull ,port side, from where the gally would be forwad and just under where the hull and deck come together. This seems to be thinner than most other(all boats I have checked) and I read where that they are sailed off the atlantic coast , great lakes, etc. You have to get into some heavvy weather and does this not present a concern?
I am new at sailing (about a year) and have owned a 1982 Mac 25 for about 8 months. When I trailered my 25 had a very large indention ( bigger than a dimple) on the bottom starboard just a little aft. Somewhere I read that, when you put your boat back in the water, you should wait for about a week to make your final adjusts to your shrouds and fore and back stays until the bottom smooths out? I can't find it again but it gave me the indication that a warped bottom while on the traileris normal. I am a little confused as to where my bunk boards are too ridged or too weak. I am guessing too ridged from the way the bottom looked. It is not a big deal just now as I have it in a slip but am going to check with the Macgregor Co. for their response. Another subject and concern is the thickness of the hull ,port side, from where the gally would be forwad and just under where the hull and deck come together. This seems to be thinner than most other(all boats I have checked) and I read where that they are sailed off the atlantic coast , great lakes, etc. You have to get into some heavvy weather and does this not present a concern?
My Best Guess
Chris, My best guess is that at some time in the past your Mac 25 was left on the trailer for a loooong time, in the extreme heat of a Southwest summer(s), with the keel fully retracted and NOT resting on the trailer. Holding up an extra 700lbs of keel is what has mis-shaped your hull. My Mac came from Phoenix and that was the explanation given to me. It doesn't affect your hull speed at all. Ol' Dave
Chris, My best guess is that at some time in the past your Mac 25 was left on the trailer for a loooong time, in the extreme heat of a Southwest summer(s), with the keel fully retracted and NOT resting on the trailer. Holding up an extra 700lbs of keel is what has mis-shaped your hull. My Mac came from Phoenix and that was the explanation given to me. It doesn't affect your hull speed at all. Ol' Dave
Bunkboard pic
Its amazing how much bending this spot on the stb. bow does and still springs back. Oddly enough, the thinness and quality are assets on trailers and off. Thin means flexible, which means no cracking gelcoat, excess weight, etc. Macs aren't meant for extreme weather for several reasons, but I've never been concerned about hull sections. Here's the promised picture, please excuse the CSC streaking and the absence of saltwater. You can see how much further the boards can be extended; the drawing is for the other side but illustrates the bevel. Tom, maybe 8" boards would work fine, as long as they don't pinch the vee up front. You may have to cut them back at the end. Bruce, if the support post looks too high, then its probably weak boards not doing their job. MacGregor didn't anticipate this problem in their minimalist designs. John s/v Lyra V-222
Its amazing how much bending this spot on the stb. bow does and still springs back. Oddly enough, the thinness and quality are assets on trailers and off. Thin means flexible, which means no cracking gelcoat, excess weight, etc. Macs aren't meant for extreme weather for several reasons, but I've never been concerned about hull sections. Here's the promised picture, please excuse the CSC streaking and the absence of saltwater. You can see how much further the boards can be extended; the drawing is for the other side but illustrates the bevel. Tom, maybe 8" boards would work fine, as long as they don't pinch the vee up front. You may have to cut them back at the end. Bruce, if the support post looks too high, then its probably weak boards not doing their job. MacGregor didn't anticipate this problem in their minimalist designs. John s/v Lyra V-222
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