Is aluminum much lighter than fiberglass? Metal fatigue on old hulls?

[62Scout]

Currently have a '69 16 foot fiberglass triull bowrider with an 85HP OB...found out it's a bit heavy behind the Jeep. It works, but there is a definite feel of the "tail wagging the dog" at times. For now, I'm towing it with an F350 dually...a wee bit of overkill. I was looking at replacing it with a 50's 16 foot aluminum hulled boat...not entirely sure what the replacement boat is, but appears typical of the era - relatively stripped down closed bow hull, minimal seating, 35HP OB, etc. As is my current boat, just with a considerably larger engine.

I've been reading a bunch of websites where it's said that aluminum is lighter than fiberglass, but is it really a significant difference? I see where it's also louder than fiberglass, and doesn't cut the water as well, but a trihull isn't exactly a great wave chopper either, lol. I'll always be running on small inland lakes, so I don't expect to run into massive waves. It's really the weight issue that I'm focusing on.

The other concern is that I'm reading some stuff on aluminum being prone to fatigue and cracking, though it would be easier to repair than fiberglass. Is that an issue that could make a 70 year old hull a deal breaker right there?

 

[southkogs]

Any hull, of any material, well kept can last a very long time. We've got a couple of fiberglass boats that are 14' from the 50s. They work just fine.

Aluminum will generally be lighter than fiberglass, and as a rule easier to care for.

I think you hear more about aluminum boats not handling chop well is that not too many of them are made for big water. The hull style for big water boats is different, and maybe easier to achieve in a fiberglass mold. Not that they don't have aluminum boats on the the coasts or Great Lakes, just fewer of 'em. On inland lakes and rivers, I would say you'll not notice much difference just from the hull material.

 

[89retta]

If your trailer is fishtailing , fix that problem first. Check to make sure your trailer is level when hooked up. And second is not enough tounge weight.

 

[Scott Danforth]

your 50 year old boat is probably water-logged carrying about 700# of water in the foam/wood on top of the heavier hull than an equivalent aluminum boat

as boats go, you have an old tri-hull which may be chopper gun construction which is double the weight of a cloth/matt constructed boat. that would put the hull about 500# heavier than a 16' aluminum v-hull. then add the water which is most likely in your foam and wood

for example, many 16' aluminum boats have hull weights in the 400-500# weight. many 16' fiberglass boats have hull weights in the 600-700# range. many chopper-gun tri-hulls weigh in the 800-1000# range

old chopper-gun constructed boats with water logged foam can weigh as much as 1800# for just the hull.

you can look up boat weights here http://boatspecs.iboats.com/ (gotta love this site)

I would have no problem buying a 70 year old aluminum boat (I have a 50's 14' fishing boat). I would probably never consider a 50 year old fiberglass boat unless it was locked in a museum since day one and never exposed to water or it just went thru a restoration. there are some well-cared-for examples, however they are the exception and not the norm.

 

[62Scout]

If your trailer is fishtailing , fix that problem first. Check to make sure your trailer is level when hooked up. And second is not enough tounge weight.

Trailer is fine. Tows straight as an arrow behind the F350. Problem is the lifted Jeep that weighs about 2500lbs ready to roll. I want to use the Jeep to tow the boat to some of the more remote lakes with less than ideal launch areas as I'm not wild about running a 10K pound diesel dually down some of the dirt roads as it's not a fun time maneuvering it down a tight road or getting that behemoth unstuck, lol. That's the other reason I'm looking at smaller, lighter weight boats.

 

[Scott Danforth]

have you weighed your rig?

also, short wheel based vehicles like your jeep really suck at towing as the trailer can push them around a bit.

 

[bansil]

Came to post about that trihull being waterlogged...and if trailer is wagging you need more tongue wt.

everything said so far sounds correct

My 24 ft pontoon pushes my 02 Tahoe around, now hooked to my 03 4x4 F250 7.3 rig, I forget it's back there, so I bet that tri-hull weighs more than your jeep now...somewhat kidding

 

[55Crestliner]

I saw your post before there were replies, and when I came back to write, there were already excellent responses.

I have probably a much shorter motor boating career than many here, only since 2004, and all I really know is aluminum. OLD aluminum like you mention. I have 3 aluminum boats from the 50's and 1 from 1949. All I can say is that they are still holding up VERY well, except for the '49, which was severely abused. With an aluminum, what you see is what you get. As has been mentioned, your fiberglass boat is probably a lot heavier than it was when it was new.

Only real issue with most '50's aluminum boats is that they are usually flat bottom in the last 30-50% of the hull, and also the forward shape is convex. This does not translate to doing very well in chop and large waves. But you did mention that you will be on smaller lakes. If that's the case, then I highly recommend one. That hull shape is great for smaller waters and smaller motors.

 

[62Scout]

My 24 ft pontoon pushes my 02 Tahoe around, now hooked to my 03 4x4 F250 7.3 rig, I forget it's back there, so I bet that tri-hull weighs more than your jeep now...somewhat kidding

I'm sure it does, lol. I have plenty of power and brake to handle the load, I just don't have enough weight, and the suspension is a bit soft as well. But that's why I want to go to an overall lighter set up on the boat side, and bonus - lighter boat/smaller motor would mean less fuel usage as well.

 

[62Scout]

I saw your post before there were replies, and when I came back to write, there were already excellent responses.

Heh..and you posted while I was writing up the other reply.

I grew up on the Great Lakes, and Lake St. Clair...I do remember Dad's 19ft Formula fiberglass was a considerably more comfortable ride when the waves got bigger compared to my Uncle's aluminum boat...that thing was just absolutely brutal when the white caps came out, though not to say the Formula was like riding on a cloud either, lol.

The 3 semi local lakes to me now are 3sq mi, 12 sq mi, and 33 sq mi in size...quite a bit smaller than even Lake St. Clair at 430 sq mi. Big waves are a rarity outside of a storm rolling through, and I wouldn't be on the water in a storm here anyways. While I remember getting caught in a few back in Michigan, as we could have potentially been 25+ miles away from the dock, and those storms popped up quick...here I'd be at most 5 miles away from the launch site. Even if a storm popped up quick, it's also a quick dash back to the launch, so I'm not all that concerned about it.

 

[62Scout]

have you weighed your rig?

also, short wheel based vehicles like your jeep really suck at towing as the trailer can push them around a bit.

It really is that light...I built it from the ground up. I know it's not ideal, but neither is a crew cab long bed diesel dually for where I want to take it.

 

[Scott Danforth]

It really is that light...I built it from the ground up. I know it's not ideal, but neither is a crew cab long bed diesel dually for where I want to take it.

not doubting the weight of the jeep, they dont weight much. talking about the boat.

 

[62Scout]

not doubting the weight of the jeep, they dont weight much. talking about the boat.

Oh, then no. I estimated it to be around 1500lbs total, based on hull weight as listed in the original sales literature, 300lbs for motor, 300lbs for trailer, and gear/fuel/etc carried on board. I suppose at this point it could be 2000+....End result is that whatever it weighs, it's definitely on the upper limit for my comfort level. Going down a back rural road isn't much of an issue, but I certainly wouldn't want to pull it across the county on heavy traffic roads like this.

I previously had been pulling it with a Suzuki Vitara that had around a 2800lb curb weight, and it seemed to control the boat OK, but was definitely lacking in the power and braking area. I really think if my suspension wasn't so soft and flexy, it wouldn't be anywhere near as bad, but it was built for rock crawling, not to tow stuff around. On the other hand, I'm really not at all attached to this boat, as it was a dirt cheap purchase just to make sure I really wanted to get into boating. I got it cheap enough that I wouldn't at all be heart broken even if I had to just sell the motor, and scrap the hull.

 

[bansil]

had a fiberglass tri hull, hated the bow slap, it weighed a lot and was soft...ran her for 3 years snd sold her, no money lost...she was a pig...but! Still on the water...enjoy her, she is like most wo..urgh nevermind
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[Scott Danforth]

Weigh the boat. A lot can happen in 50 years

 

[62Scout]

Not really sure what the point of dragging it 50 miles to work and weighing it is going to accomplish now, other than reinforcing the idea that going to an aluminum hull is a better plan now? As I said..I'm not at all attached to this particular boat in any way, and I'd just as soon scrap the hull before undergoing a gut/rebuild project on it.

 

[Lightwin 3]

Aluminum boats make it relatively easy to spot problems. Look for cracking around stress points such as joints, transom, chines, etc. If something like the transom or deck (floor) wood is rotten, it's MUCH easier to fix than a glass hull.