Sailboat building and hull worthiness myths

[KetchJohnB]

We have been cruising for 8 years, all over. If you can crash the boat into an un-charted reef and it does not leak, that is a good boat. Most places in the world are not well charted. Nothing to do with engineering. Rule of thumb...poured in keel, not bolted on Those just crunch.

[raahell]

Hi Steely Dancer,
I wouldn't worry about the fact that it is made in alu alloy. That can only be a bonus. I don't know where you got the idea that GRP repairs are easier than metal. In terms of diagnosing and locating the problem AND in terms of the actual repair, working in metals is easier than GRP. In all cases you might have to learn some new skills but that comes hand-in-hand with boat ownership, unless you're rich and can hire others to do all the work!

The boat is well priced, assuming there's nothing intrinsically wrong with the vessel. In fact it is VERY well priced if you compare to any other comparably sized alu alloy boat on the market.

The most damaging thing for metal boats and especially alu-alloys, is galvanic corrosion due to poor electrical work, either in the boat, or from shore power systems, or an adjacent boat that is emitting stray current. This can eat away at a metal boat rather quickly. Many metal boats have an isolation transformer to deal with the shore power problem. I'm not sure if the Victron device pictured in the ad is one, but Victron does make isolation transformers. Well worth the investment.


There are some features that many contemporary sailors would not like, such as the vertical and deep main companionway and the hump and traveller in the cockpit that you have to climb over to get from cockpit to companionway. My wife just looked at that and discounted the boat immediately. It's good to be young(ish) and sure footed if you're going to be the next owner.

The draught may also be a concern depending on where you're planning to sail. On the other hand, that deep keel, high aspect rudder and fine hull form, she's likely great upwind. In my case we bought a metal boat with swing-keel which has the option of shallow (2.5') or deep (6.5') draught, depending on circumstances we face at the moment. There are lots of French Alu-alloy sailboats with this feature but you'll pay a lot more than $70G to get a used one.

If I was younger, had a more agile partner, was living in the US and hadn't already just bought a metal sailboat, I would not pass up the opportunity to at least look at the vessel.

One last suggestion: If you're seriously in the market for a metal boat you might consider purchasing an ultrasonic thickness gauge. I just bought a good quality, lightly used device for $80 and have been measuring the plate thickness on parts of my metal boat to determine the kinds of remedial work I might have to do. It's probably the best way to do non-destructive, non-invasive measurements of a hull or deck. Just add a small dab of conductive gel to the location you want to measure, then stick the probe to it, take the reading, then wipe away the gel. No owner is going to mind that. If s/he does, s/he's hiding something! A good metal boat surveyor is going to have one and will take several dozen measurements in a pre-purchase survey. For the same price that you're paying him/her to do the measurements, you could buy one and then continue to use it over the term of your ownership.


Good luck with your search!

[Cheechako]

Originally Posted by Notyetsinking

Hi,

So I've been reading these forums quite a bit as there is a wealth of knowledge here regarding any number of things to do with the world of sailing. As someone looking to buy a boat in the next couple months, this knowledge has been invaluable. However, one thing I have continually come across is the myth of hull thickness corresponding to the boats strength, especially in comparing old boats to new ones. In particular, I have seen 'for a blue-water boat with a thick hull' or any variation indicating that a thick-hulled boat is inherently better. From what I understand, this is misleading at best, and flat out wrong at worst.

A little background; I am a young engineer, so I don't have the experience of many on this forum. I see this as having both strengths and weaknesses, as I am more accepting of new ideas since I don't have personal experience to delineate between new and tried and true. That last part there is the weakness; I don't have experience , only theory.

So now that I have established that, I this article is the best source I have found on hull construction: https://www.boats.com/reviews/fiberg...ng-a-laminate/

In this, I would really like to highlight the comparison between uni-directional fiberglass vs mat, woven roving and chopper-gun built boats. Obviously vacuum-bagging would result in a much lighter and stronger boat than one built without it, so I won't go into that. Anyway, the danger I mentioned earlier between saying a heavier boat being inherently stronger comes into full focus here, as I believe many if not all older boats were built using either chopper-gun, woven-roving, or mat fiberglass. Though in certain instances I imagine a mat etc. built boat would be stronger, by and large a lighter, thinner boat using uni-directional glass will be much stronger as its strength is equally distributed across all impact angles. Without going into the math of it, as admittedly my materials science is a bit rusty, I'll give an example. Think of Mat fiberglass as the cinderblocks people are able to break stacked on each other like this guy:
he is able to break all of those blocks as their resistance against a perpendicular force is very low, and as they are uniformly stacked on each other that force is linearly passed onto the next block. If these blocks were instead stacked across each other with the centers of each block varying at each layer, only the first block would have(probably) broken. I understand this is not a perfect example, but I hope it is accurate enough to illustrate the point.

I fully expect I am wrong on some aspects here, and am very open to learning other peoples inputs. However, I wanted to put this out there as I know there are many new and potential sailors who wouldn't know to consider this complexity. Please let me know what you think

There's "stronger" in terms of stiffness, there's "stronger" in terms of impact resistance, there's "stronger" in terms of resistance to flexing, there's a number of "strengths" to be considered I suppose.

As an engineer you probably understand Modulus of Elasticity. It's amazing how flexible some boat building materials are. If you take a strip of material 1/4" thick x 2" wide and clamp it with 2-3 feet hanging off a rigid table, the difference in how it bends from gravity or a weight comparing steel, aluminum and fiberglass resin layup is amazing. Aluminum, although it may be rated with strength equal to steel, being far less rigid than steel....will flex a lot. Fiberglass even more so.

I bought an over size hydraulic backstay adjuster for my 44 ft boat. The specs for what I needed were on the border between two models, so I bought the big one. What I realized eventually was that I could bend the boat by 3-4 inches! trying to make the forestay straight! This was a cored glass boat with two huge stringers, probably 4.5" x 3" high on the bottom inside of the hull.

[Steely Dancer]

Originally Posted by Orion Jim

A proven ocean cruiser....I would buy the ex-RAN in a heartbeat. Of course an intensive survey is necessary.

Thank you! Yes, a survey, of course. Trying to get the big ticket items cleared away with the seafarers here first.

[Steely Dancer]

Originally Posted by raahell

Hi Steely Dancer,
I wouldn't worry about the fact that it is made in alu alloy. That can only be a bonus. I don't know where you got the idea that GRP repairs are easier than metal. In terms of diagnosing and locating the problem AND in terms of the actual repair, working in metals is easier than GRP. In all cases you might have to learn some new skills but that comes hand-in-hand with boat ownership, unless you're rich and can hire others to do all the work!

The boat is well priced, assuming there's nothing intrinsically wrong with the vessel. In fact it is VERY well priced if you compare to any other comparably sized alu alloy boat on the market.

The most damaging thing for metal boats and especially alu-alloys, is galvanic corrosion due to poor electrical work, either in the boat, or from shore power systems, or an adjacent boat that is emitting stray current. This can eat away at a metal boat rather quickly. Many metal boats have an isolation transformer to deal with the shore power problem. I'm not sure if the Victron device pictured in the ad is one, but Victron does make isolation transformers. Well worth the investment.


There are some features that many contemporary sailors would not like, such as the vertical and deep main companionway and the hump and traveller in the cockpit that you have to climb over to get from cockpit to companionway. My wife just looked at that and discounted the boat immediately. It's good to be young(ish) and sure footed if you're going to be the next owner.

The draught may also be a concern depending on where you're planning to sail. On the other hand, that deep keel, high aspect rudder and fine hull form, she's likely great upwind. In my case we bought a metal boat with swing-keel which has the option of shallow (2.5') or deep (6.5') draught, depending on circumstances we face at the moment. There are lots of French Alu-alloy sailboats with this feature but you'll pay a lot more than $70G to get a used one.

If I was younger, had a more agile partner, was living in the US and hadn't already just bought a metal sailboat, I would not pass up the opportunity to at least look at the vessel.

One last suggestion: If you're seriously in the market for a metal boat you might consider purchasing an ultrasonic thickness gauge. I just bought a good quality, lightly used device for $80 and have been measuring the plate thickness on parts of my metal boat to determine the kinds of remedial work I might have to do. It's probably the best way to do non-destructive, non-invasive measurements of a hull or deck. Just add a small dab of conductive gel to the location you want to measure, then stick the probe to it, take the reading, then wipe away the gel. No owner is going to mind that. If s/he does, s/he's hiding something! A good metal boat surveyor is going to have one and will take several dozen measurements in a pre-purchase survey. For the same price that you're paying him/her to do the measurements, you could buy one and then continue to use it over the term of your ownership.


Good luck with your search!

JUST seeing this—wow, thank you! Lots to chew on. We come to this listing after having been outbid on a 1977 Nautor's Swan 411—similar deck features and companionway issues. Arguably more beautiful and less tank-like, especially if you ask my wife.

Planned sailing area is the Salish Sea. Not sure how that will affect/be affected by draft.

[raahell]

Hi Steely Dancer,


Salish Sea! Never been there but it looks pretty awesome.

I'm going to assume that you're fairly new to sailing/boat ownership so forgive me (and don't be offended) if I give you some info that you already know.

In terms of answering your question about a boat's suitability for any sailing destination, I would seek to answer the following questions:

• What are the minimum depths in harbours, marinas and clubs in that location?
• What are the typical anchoring depths in the recognized anchorages?
• What are the predominant characteristics of the sea bottom?
  • Soft or rocky?
  • Slow/predictable or rapid/unexpected changes in depth?
• How much do the tides turn safe waterways into obstacle courses?
• Salish sea is a long and fairly narrow channel running North/South. Are the winds predominantly up/down the waterway, or across?

If the Salish Sea has predominantly soft sea bottom, regular, predictable changes in depth and fairly deep locations for docking and anchoring, and the winds are mostly up/down the seaway, then a deep draught boat with good upwind and downwind performance makes excellent sense.

If the sea bottom is characteristically rocky and unpredictable, anchorages/docks are often shallow (or regularly become so due to tidal effects), having a shallow(er)-draught boat will make more sense, since it exposes you less to groundings and allows you to get into port or anchorages in most/all conditions. The rub here is that shallow draught often means less than favourable upwind performance. But if the winds in the area are mostly Westerly (across the seaway) then that's less of an issue.

BTW most sailors would consider anything >6' as deep draught, while <5' is in the shallow range. Not surprisingly, most cruising boats inhabit the safe middle of 5'-6'. Many production models offer keel options ranging from shallow to deep, which complicates your search.

The more one researches, sails and owns a sailboat, the more one realizes that every feature inherits both positive and negative aspects. There are lots of sailboat owners in the Salish Sea. If you haven't already, join one of the on-line cruising forums dedicated that area and find out what sailboat features owners gravitate to for safe sailing in that region.

https://salishseapilot.com/

https://sailish.com/

That will help you to articulate your own requirements. Beware, however, that people tend to follow the beaten path of popular makes and brands of sailboats, ignoring hidden gems that are out there. Better to list your requirements in terms of boat features/amenities and sailing/safety parameters. Then keep an open mid to the actual offerings on the market that fit your requirements.

Good luck with your search! you're in a part of the world that makes sailing a perfectly sensible thing to want to do.

[Steely Dancer]

Originally Posted by raahell

Hi Steely Dancer,


...

Thank you AGAIN! These are amazing resources, and you are more or less correct in your assumption: I'm fairly new to boating but I'm a fast learner and I will be checking out all these questions and links, probably diving pretty deep into them as rabbit holes.

My sense is that most boaters in the Puget Sound and points north around Vancouver Island and into southern Alaska are able to keep pretty deep drafts. And if not, there are plenty of deeper anchorages and routes to choose from, so we're able to be versatile in our boat search where that particular attribute is concerned.

Lots to continue to get educated about. I truly thank you again for your help!