Wood Boat / Fiberglass Boat Weight Comparison

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BayouBengal
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Wood Boat / Fiberglass Boat Weight Comparison

Postby BayouBengal » Sun Sep 10, 2017 12:11 pm

This morning I did something that I've wanted to do for a while; I weighted my boat. After subtracting out my truck, trailer, and the fat boy driving the truck, my boat came in at about 3900 pounds. I was curious as to how this compared to similar fiberglass boats. My boat length is 20'8". Adding the swimdeck, the total boat length comes in at 22'6". My beam is 94". My motor is the 4.3L mercruiser with an Alpha 2 outdrive. I weighted the boat with all the gear in it including life jackets, bumpers, ropes, anchor, paddle, etc.. I had approximately 20 gallons of fuel in the boat.

So I know what my boat weights, but the difficult part now is determining what similar fiberglass boats weight. It seems when you look at specs, they seem to list weights in a multitude of ways, some seem ridiculously low, some seem somewhat high.

Anyone have any opinions on whether my boat is heavy for it's size, light for it's size, or about normal as compared to similar fiberglass runabouts?

DSR
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Re: Wood Boat / Fiberglass Boat Weight Comparison

Postby DSR » Sun Sep 10, 2017 12:56 pm

Hi Bayou,

It's not really a direct comparison, but a friend has a 20' Malibu Response (which I've been told is fairly light for a ski boat) and it has a dry weight of 2900 lbs. That's with nothing in it (not even gas or oils.....)

I don't know if that helps or not. It's a question I've been curious about myself.

Thanks,
Dave
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galamb
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Re: Wood Boat / Fiberglass Boat Weight Comparison

Postby galamb » Sun Sep 10, 2017 4:07 pm

Can give you a few numbers for maybe similar boats from boat test dot com:

Robalo R207 - L 20' 7" B 8' 4" Dry WT 3500 lbs Tested WT 4200 lbs (with a 150 hp Yami outboard)

Triumph 195 DC (ok, it's abs not fiberglass) L 20' 0" B 8' 2" Dry WT 2000 lbs (no engine) Tested WT 2700 lbs (with a 115 hp Yami outboard)

Hydra-Sports 202 DC L 20' 1" B 8' 6" Dry WT 2965 lbs (rigged hull, no engine and no gas/batteries etc - showroom new)

Couldn't find any numbers for similar size with an I/O....
Graham

Yes, Plywood is "real" wood :)

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Bill Edmundson
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Re: Wood Boat / Fiberglass Boat Weight Comparison

Postby Bill Edmundson » Sun Sep 10, 2017 4:28 pm

Jeff

The Bartender 24'x8'-4" 45 gal gas, 115 hp Yamaha and 31 gals of water, estimated at 3800#. I have not backed into performance numbers. But, with 600# of people and about half the gas I got to 35 mph WOT.

Bill
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JimmY
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Re: Wood Boat / Fiberglass Boat Weight Comparison

Postby JimmY » Sun Sep 10, 2017 4:49 pm

I think the cool factor takes off a few hundred pounds. :D
-Jim
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BayouBengal
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Re: Wood Boat / Fiberglass Boat Weight Comparison

Postby BayouBengal » Sun Sep 10, 2017 5:25 pm

Revaluating everything, I think I'm at about 3700 pounds. I estimated my tandem axle trailer at 850 pounds and it's probably more than that. I also think I underestimated my truck weight considering all the tools and stuff I'm carrying in it. At 3700 pounds, I'm thinking I'm probably about equal weight to a typical commercial fiberglass runabout.

Not that it really matters at this point, I'm sure not going to change anything. Building light was not my focus during construction, but I certainly tried to make it adequately strong while using minimal materials. There was some design issues though that conflicted with that, namely two sets of motor stringers, completely trimmed and dressy interior, and an extremely hefty shear shelf just to name a some.

But I was curious about the weight from a couple of aspects. One, I always hear that wood boats are lighter than fiberglass, but maybe not so much now that I've weighted it; and two, speed. The boat honestly feels very fast to me and I'm surprised by it because I thought I'd be a little under=powered with a six instead of an eight. I'm no speed demon but I am interested in what the top speed would be. Why, I don't know, because really all I want to do is ride around at 25 to 30. On the rivers I've been running on, I've not gone full throttle because I'm too worried about logs in the water. The fastest I've been in the boat has been a little over 40 as measured by the speedometer (which may not be so accurate).

At the Gathering, I want to speed test it on flat early morning open water with a GPS. Any volunteers for a co-pilot?

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Bill Edmundson
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Re: Wood Boat / Fiberglass Boat Weight Comparison

Postby Bill Edmundson » Sun Sep 10, 2017 5:41 pm

Jeff

I'm sure a co-pilot is no problem.

Bill
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vupilot
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Re: Wood Boat / Fiberglass Boat Weight Comparison

Postby vupilot » Sun Sep 10, 2017 6:17 pm

Ill charge up my GPS. I'm light weight so I shouldnt hinder your performance much :D

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Re: Wood Boat / Fiberglass Boat Weight Comparison

Postby JimmY » Mon Sep 11, 2017 9:34 am

BayouBengal wrote:Any volunteers for a co-pilot?


Pick me! Pick me!

Crap, I can't make it this year. :(
-Jim
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Bill Edmundson
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Re: Wood Boat / Fiberglass Boat Weight Comparison

Postby Bill Edmundson » Mon Sep 11, 2017 11:15 am

The 3800# must have been my trailering weight. When I back in from the weight to HP ratio I must be about 2800-2900# running weight.

Bill
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mrintense
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Re: Wood Boat / Fiberglass Boat Weight Comparison

Postby mrintense » Mon Sep 11, 2017 1:14 pm

I had a discussion with another Vera Cruise builder a few years ago and he told me that his Vera Cruise (with trailer) but otherwise not loaded came to 3500 pounds. It was a dual axle trailer (steel). The Vera Cruise is also 21 foot although he had a fairly small outboard on his boat (25 HP). Assuming a trailer is in the neighborhood of 800 to 1000 lbs, that would put the boat weight with a larger sized outboard at around 2800 pounds (assumes 100 lbs more for the engine and the 800 lb trailer weight). I do not know what size fuel tank he has of it he has one or two batteries. Assuming that your engine probably weighs a bit more than an outboard, it would seem to me that 3000 to 3300 pounds would be about right.

From your last comment, it sounds like you underestimated the truck and trailer weight which would make your boat lighter, probably be a significant amount. If you can , get the trailer and truck weighed separately to get a definitive answer.
Carl
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BayouBengal
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Re: Wood Boat / Fiberglass Boat Weight Comparison

Postby BayouBengal » Mon Sep 11, 2017 2:36 pm

When I back in from the weight to HP ratio I must be about 2800-2900# running weight.

Damned Bill, your boat is featherweight. Of course I missed seeing your boat last year. Really looking forward to seeing it and hopefully riding on it too. It's certainly a neat design.
Crap, I can't make it this year.

Change your plans. You and Chris can both come. It's no big deal how fast it will go, but if ever the need arises to brag on how fast it is, the extra weight of both of you being in the boat will give me the leeway to honestly :lol: state the top speed at 12 mph faster than whatever Chris measures.

I guess I just have a heavy boat and that should be no surprise to me with the way I loaded it down while trimming out the interior. Here's the numbers from the scale - 3820 Front Axle Weight, 2060 Rear Axle Weight, 4380 trailer axle weight, 10260 overall weight. Truck is a 2014 Silverado Crew Cab, Trailer is 6" I-Beam aluminum tandem axle. I've got to figure the 3700 pounds is probably about right. The scales are only about 2 miles away from a boat ramp; so, if I really, really, really want to know, I could weight it, drop the boat off, then go back and just weight the truck and trailer.

The GPS test should tell the tale. Judging from the speedometer and tach with the amount of throttle I've given it, the boat should hit 60 at full throttle; and that's why I thought the boat must be very light. But now I suspect the speedometer could very well be way wrong. If the boat actually weights 3700 pounds, I can't comprehend 60 mph with a 4.3L and Alpha drive.


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