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Old 01-19-2015, 09:57 PM   #66
Scraping Paint
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Originally Posted by manyboats View Post
To again take a poke at what I'm talking about let's take a look at the GB 36 single. What is usually it's top speed? And what is it's displacement? To hear form several would be preferable.
Eric--- Before we bought the cruiser we have now, we chartered a 1991 GB36 with a single Cummins 220 hp engine. We were told that the best cruise setting was 2000 rpm which gave the boat 8 knots pretty much right on the nose.

In contrast, we run our two FL120s at 1650 rpm, which gives us 8 knots.

I do not know what the top speed of the single engine GB36 is as we never had occasion to find out. My guess is that with the 220 hp Cummins at WOT it was in the neighborhood of 12 knots.

The displacement of the 1991 single-engine GB36 is probably slightly less than ours. Our boat by the Travelift scale is 30,000 pounds with full fuel, water, and all of our "stuff."

As the boat we chartered is a 1991 model, it would have been built somewhat lighter than our 1973 boat which, as fiberglass was a brand new material for American Marine, was overbuilt in terms of the hull and deck thickness.

The owner's manual displacement for our boat is 26,000 pounds empty weight. The single-engine version of our boat weighs appropriately less.

The GB owners forum manuals section does not contain a manual for a post-1988 single-engine model GB36, so I can only guess at its displacement. (1988 was the year American Marine began using brand new molds for the GB36 and GB42 and the boats changed a bit in terms of dimensions and layup). But I would guess that the displacement of the single-engine 1991 boat we chartered was in the 26,000-28,000 pound range.
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