Weird hull modification

[Woody]

The marina called last week - they had our A25 in the shop for some mid-winter maintenance, and wanted to show me something...

Seems when they brought her in from the cold, they noticed water leaking out from the rudder shaft. But there was no sign of water inside. They finally figured out that at some time in the past a second hull had been built under the main hull at the stern. There was a space between the new layer and the original, and it had been stuffed with foam. Water had leaked in around the rudder shaft, and soaked the foam!

We have no idea why this modification was made - presumably someone thought it would improve performance somehow.

The mechanic cut away an area of the outside layer to remove the wet foam and dry out the area. Then he will seal it all up, this time with a FRP tube surrounding the rudder shaft so the problem will never recur.
Here are some photos...

I drew a dotted line approximately at the bottom of the original transom.

3-HullMods.JPG

Here's another view - you can see how the added piece changes the line towards the stern.

2-DSCN2350.JPG

Here's where the mechanic cut away an area around the rudder shaft opening to inspect and clean out the space...

1-DSCN2348.JPG

I was browsing for possible explanations, or other examples of people modifying the hull shape, and came across this... (my boat looks like nothing compared with this guy's)
http://www.albin-25.nl/ENGELS/Ingezonde ... 0Albin.htm
Check out the video of his A25 going 15 knots!

[NickScheuer]

Tht is really weird, Woody! What motor do you have? Does your boat have the "hook" on the bottom just forward of where the bottom ends at the transom? If so, it would seem that a prior owner wanted to accentuate the "lift" the hook provides. Or, they might have merely wanted to have more of the hull immersed aft, possibly in order to support more weight.

I'd worry that at slow speed your hull would be dragging an awfull lot of immersed transom in the water.

Have you got th original Owner's Manual written by Per Brohol? The line drawing on the first page inside the cover looks nothing like your hull. The line drawing in my Manual does not show the slight "hook" on my 1976 Albin-25, which is a feature added just bit prior to that time. The drawing shows very little of the transom being immersed when the hull floats on her design waterline. My boat has just a little more immersed transom due to her "hook", which is further evidenced by her filthy waterline.

Nick

[Woody]

Hi Nick,
Thanks for your reply.
I do have the original manual - that's what I used in order to guess where the original bottom of the transom was (my dotted line in the photo). I don't know anything about the 'hook' you mention - do you have a photo of your boat that shows it? On ours there is no sign of a hook near the center, and the added layer is very close to the original hull along the center line. But the built-up chines do dip down toward the stern now.

The engine is a 27 hp Westerbeke with max rpm of 3000. Top speed is just under 7 knots, and we usually cruise at 2700 rpm which gives us about 6.4 knots - I'm hoping to get a bit more after the marina cleans up the hull for me - it's pretty rough right now and I suspect a smoother surface will go faster. If not, I might try a different prop.

[NickScheuer]

27-hp sounds like enough; I was wondering whether you had more "omph" than the 21-hp output from the early AD21 Albin engines.

If your boat had the "hook" in her bottom, it would be pretty well covered up by the additional foam-filled shape. Whereas the hull line drawing shows the Albin-25's botton rising in a fairly straight line to the transom, the "hook" gives the bottom a bit of "reverse curve". I have no photo of that area of my hull, but judging how my hull rests on a pair of dead-straight bunk boards, I'd say my bottom/transom edge is perhaps 3/4" lower than it would be were the bottom shaped like the line drawing.

Nick

[Woody]

Nick,
I suspect my boat is pre-'hook'; the hull number is 1222 (1972 vintage). There's no way to know for sure now it's all covered over with the additional layer.

Yes, I thought the 27hp Westerbeke should have no trouble pushing her to the hull speed, which looks like 8 knots from the original manual charts. It would be nice to have that extra knot sometimes as long as there's no fuel penalty for normal cruising.

Even if she's a bit quirky, we've been enjoying her very much, and looking forward to some cruises this summer. We keep her on the Rideau Canal system, so can go to Ottawa or Kingston, and from there pretty much anywhere.

[NickScheuer]

Our first real adventure will be a tow to Lake Champlain in mid-summer, visit wife's Norwegian cousins in Burlington, then exit down the Champlain canal to Troy, NY. We'll then head west along the Erie Canal for several days. The cousins will come pick me up so I can retrieve our truck.

[hetek]

It is my understanding that the hook began with the 1973 year boats and the "Deluxe" model designation. A 1972 would indeed be "pre-hook".

I made some inquiries once and found that even the pre-hook boats could exceed hull speed. However, most say that they had a "squat" to the stern while at the upper end of the speed range. Perhaps that's why Albin redesigned the hull with the hook in order to give it some lift to the stern.

There is also a rumor regarding the hook on the post 1973 boats and if it was indeed intentional. The rumor is that the mold warped during curing and that the hook was unintentional, but, as the painter Bob Ross would call it, a "happy accident". The hook proved to be a benefit to performance.

However, there is clearly a difference between the pre and post-hook boat hulls, besides the hook itself. The transom shape is one obvious difference. The pre-hook boats have a point to the bottom as your dotted line shows, while the post-hook boats have a flatter bottom.

Quite the modification to your hull though. Not a small undertaking to do that.

[NickScheuer]

Thanks for mentioning the "point" at the center of the transom on the original model 25's, hetek. My 1975 definately exhibits a shallow arc across her transom. This detail proves that the line drawing appearing in the Owner's Manual shows the original hull, further evidenced by the lack of any reverese curve on the buttock lines.

[Woody]

Nick,
That sounds like a great adventure! Have fun!

Hetek,
Thanks for the history - very interesting.

The dotted line I drew on my transom is based on the original drawings - I have no idea what the original hull shape of my boat was, since it's now covered up with a secondary layer. This 'new' shape does add a bit of 'hook' at the outside corners of the transom now, as well as changing the transom shape to a curve instead of a point - perhaps whoever added it was trying to emulate the newer hull design.

Another thought I had was maybe my boat was a factory prototype for the 1973 hull, since the added hull layer seems to have been well done and nicely integrated (except for the eventual leakage around the rudder shaft).

It would be interesting to see several A25s of different vintage out of the water at one time to compare hull shape!

[hetek]

...perhaps whoever added it was trying to emulate the newer hull design.

Another thought I had was maybe my boat was a factory prototype for the 1973 hull...

Make the older boat look like it has the newer hull? That's what I first thought. The additional hull bottom closely resembles the later Deluxe hull's transom (rounded, without the point).

Reminds me of the story about the owners of 1963 Corvettes with the split rear window who were envious of the new 1964 Corvette with their solid, one piece rear window. In order to make their 1963 car look like the newer 1964 car, they would remove the two rear windows, cut out the dividing bar, do the necessary body work and install the 1964 window. Presto! New Corvette! And it won't hurt the value of a 1963 Corvette in, oh... say 40 years, will it?

Bet they're kicking themselves now!

Albin has also been known to produce a couple prototype boats that have made it into the general population, so I guess anything is possible. Your 1972 boat is on the cusp of the hull redesign, so you never know...