mid cabin - stringer and limber hole sealing

[BobCT]

I spoke with one of the forum members the other day (Todd) who was nice enough to call me back after stumbling across his post about stringer replacement in his '86 mid cabin. This was before my time but his pics were impressive.

I looked at several mid cabins before I bought mine and all had some stringers issues. After speaking with Todd and re-reading his original post, I think he's discovered the root cause.

All of the cross support to stringer connections AND limber holes are either not sealed at all or done very poorly. Now that I've looked more closely, they're pathetic really. Big voids in the gelcoat which allow straight access to the stringers. The round limber holes (the ones that look like PVC pipe) are not sealed well at all especially after 20 years or so.

I know Todd posted this before but anyone with a midcabin should think about a methodical fix on each of these areas with either epoxy and/or sealant. Look at his pictures if you need incentive to get started

I recaulked the two round limber holes in front of the batteries yesterday (on the inner stringers). The caulk just pulled away in one piece so I'm sure water had been wicking up into the stringers for years. These short tubes are actually fiberglass even though they look like PVC. I hammered mine back and forth so I could clean them up. I might knock then completely out next year and let them dry out over the winter.

I believe these two are the lowest point in the bilge so probably a good place to start. In the meantime, keep your bilge bone dry!

My understanding is that this is really a mid cabin issue, the express models have the liner.


Bob

[Tropical Buzz]

After reading this post I did a search and read the previous threads on stringer repair/replacement. I was more than a little surprised as I had thought that Trojans were not known for stringer rot issues. My wife and I really liked the look of the 43' Wellcraft Portofinos and the 37' Corsicas but we struck them entirely off our list when we read about the stringer rot problems due to poorly sealed limber holes. I shook my head in disbelief that a builder could be so careless with a simple process that has such a direct impact on the integrity and longevity of its hulls. Did they not expect that people would actually be using their boats in the water??

When I read about the craftsmanship and solid construction of the Trojan hulls, I thought - this is more like it! I also thought that the International series boats used hollow fiberglass stringers under the engines to eliminate concerns over rotting wood affecting the engine mounts. This was mentioned as well by Davescarrs in one of the threads:

The hollow fiberglass stringer (no wood) had a square hole cut in it for access to strut backing plate. It may be different for you if your boat is not International. If you have a different type of Trojan also check the rudder packing. Good Luck! Will put boat back in water Wed, April 29, 2009 hopefully problem solved.

An online review of the 12 Meter International express (1989 - 1991) also mentions solid fiberglass I-beam stringers. So is it only the non-International series boats that are prone to stringer problems, boats built before a certain year or is it across the entire line?

[BobCT]

this can be a little confusing as there are essentially two models that look very similar from the outside. The "express" model which has the full liner from the main bulkhead back and don't have the issues that I pointed out.

The "mid cabin" - which I own , is built differently and has the more traditional wood stringer over fiberglass construction. On the mid cabins, current and future owners need to be aware of the weak points and address them immediately.

I'm still impressed with the overall construction but will spend time in order to keep the stringers dry. In the meantime, I won't allow any standing water in the bilge.


Bob

[RWS]

this can be a little confusing as there are essentially three models that look similar from the outside. The "express" model and the "express cruiser" (RWS - do I have that correct?) have a full liner from the main bulkhead back and do not have the issues that I pointed out.

The "mid cabin" - which I own , is built differently and has the more traditional wood stringer over fiberglass construction. On the mid cabins, current and future owners need to be aware of the weak points and address them immediately.

I'm still impressed with the overall construction but will spend time in order to keep the stringers dry. In the meantime, I won't allow any standing water in the bilge.

Bob

++++++++++++++++++++++++++++++++

Hi Bob,

Actually those are my terms, I'm not really sure of the Lancaster nomenclature.

I read in an article somewhere that part of the concept of the original 10 meter International was that the boat could be built into several different configurations, based on the base modular construction.

The earlier 10 meter series was available as an express cruiser, sedan, convertible (I don't know the difference between the sedan and the convertible) aft cabin, an aft cabin express crusier and an aft cabin with a bridge. This isn't exact but probably fairly close.

The mid cabin based boats came as express and convertible(or is it sedan?) I believe the aft cabin models were never offered on the mid cabin based hull.

These boats shared the same hull which featured 4 longitudinal mostly hollow stringers and a full liner in teh engine room and lazarette. The interior of the cabin was also designed as a "liner" to increase stiffening. Other than the rear engine room bulkhead, (watch these!) there is very little wood in this design.

These boats had the engines directly under the helm seats.

With the mid cabin models, the engines were moved farther aft and the cockpit floor was raised. These two changes allowed for a cabin to be located in what WAS the engine room.

The mid cabin models featured a totally different cabin layout eliminated the electric curved doors and all the curved concept design ideas from the original design. The new cabin design combined with the aft cabin allowed for far more usable and efficient use of cabin space.

The mid cabins were very, very popular.

The mid cabin models eliminated the vacuum attached full liner hull system, built in water and waste tanks and featured a return to a more conventional hull build with wood stringers and standard tanks for water and waste.

Midcabins have 2 smaller fuel tanks, cruisers have one

Although it is a different hull design, the aft cabin models also have two fuel tanks.

Midcabin generators are mounted much farther aft, close to the transom.

With the midcabin engine mounted farther aft,the shafts are shorter and require only one strut per shaft, the express cruiser has two.

The lower shaft angles equate to smaller props, however they are spinning at a faster RPM as the gear ratio is different.

Midcabins have no lazarette.

The radar arches might be taller, but this is not confirmed.

Midcabins feature two nice opaque non-opening lexan skylights built into the recesses of the deck. This is a nice feature, however there have been some reports os rebedding being necessary when they leak.

The windshields are the same height, but here are some clues to spot one from the other in the express cruiser vs. midcabin models. Many of these differences translate to other layouts.

Express cruiser 3 port windows, midcabin 2.

The Midcabin has a higher cockpit floor and shorter plexiglass sliding hatch to the cabin.

The Midcabin has a kind of filler section on the top of the gunnels to compensate for the deck being taller.

The mid cabin based models have the main electrical panel and breaker access from the galley as opposed to just below the helm.

Midcabin transom view from the rear has a cutout for the step.

There are probably numerous other differences but these are the ones I can think of.

O.K. that's the short answer.

I suppose it's an obsession, but I really have enjoyed and learned a lot from this boat and I feel very fortunate to have chosen this brand/model as I didn't know just how good they were at the time.

Yeah, definately an obsession.

RWS

[Tropical Buzz]

Thanks Bob and RWS. Was the express version of the 10M offered alongside the mid cabin throughout production or did the mid cabin replace the express after a certain model year ('83?)? Also, from a pure performance point of view, are the expresses the more desirable of the open configurations based on engine placement, with the mid cabins tending to be arse heavy/bow high and generally slower at planing speeds?

Was it as complicated with the larger express models like the 11M, 12M and 13M Internationals - rot/water intrusion issues with those models too, or did the later models like the 12M have the all glass stringers?

PS - while I'm asking, was there ever a 14M Express?

[RWS]

Thanks Bob and RWS. Was the express version of the 10M offered alongside the mid cabin throughout production or did the mid cabin replace the express after a certain model year ('83?)? Also, from a pure performance point of view, are the expresses the more desirable of the open configurations based on engine placement, with the mid cabins tending to be arse heavy/bow high and generally slower at planing speeds?

Was it as complicated with the larger express models like the 11M, 12M and 13M Internationals - rot/water intrusion issues with those models too, or did the later models like the 12M have the all glass stringers?

PS - while I'm asking, was there ever a 14M Express?

====================================

Not a fact, but my own guess based on what's been for sale is that as the mid cabin was introduced there were less of the express cruisers sold over time. The newer the 10 meter the less chance it is the original design. I suppose that at some time during production it was phased out and every hull was then based on the mid cabin based design.

As far as performance is concerned, I am not aware of any differences, as they seem to have similar efficiency and cruise numbers in general discussion. Perhaps John Leed or Bob could provide more info on that matter. I would think there would be a difference in minimum planing speed with the weight distribution issue.

My 454 speed & fuel consumption chart has been posted here numerous times and no one has commented on experiencing anything too much different.

RWS

[gardnersf]

I have heard that the midcabins cruise about a knot slower, not substantial. I don't have flow scans but I know that my rpms matched to RWS charts are a little slower.