- Well, since we re talking a planing (or semi-planing) boat and somewhere in the same time period as RM, the 15HP RM engine was pegged by Bill A at about 340# &Message 1 of 10 , Jan 4, 2008View SourceWell, since we're talking a planing (or semi-planing) boat and somewhere in the same time period as RM, the 15HP RM engine was pegged by Bill A at about 340# & 91ci. As to the smaller engines, I remember in the late 40s that 16' inboards in the Puget Sound (rental boats at "resorts") usually had a 2 or 3HP Briggs & Stratton or equivalent (Reinell and Marysville Boat Works both used that) and they moved along quite nicely at 6 or so knots (nobody really measured that sort of thing back then - it just got you there fast enough or it didn't).
----- Original Message -----
Sent: Friday, January 04, 2008 3:46 PM
Subject: [AtkinBoats] Re: Twinkle Twinkle little boat
I don't have Gerr's book yet so I suppose the spreadsheet would not
help me much. Thanks for the offer though.
Part of the problem is that I'm not sure what engine was supposed to go
in these boats originally. Typical small sizes (3hp) were often cast
iron, two stroke, make-n-break ignition. Above twenty horsepower they
were often small marine four cylinder equipped from Grey marine or
Redwing, etc. What were the in between marine motors like? A ten horse
make-n-break is heavy. That could weigh as much as the hull! I would
suppose the hull to be around 300-400lbs. This makes estimating the
weight to horsepower difficult.
I would think the tunnel would force the bow down in acceleration like
on Mr. Whites RM. The jet of water from the tunnel would pull the water
from transom and make it difficult to tell when she would be on plane.
This design is right at the threshhold of a semi-planing boat. The
concern is that she might not perform well unless very lightly loaded.
If fuel mileage in this day were not a concern I would build a Little
[Non-text portions of this message have been removed]
- ... Maybe, but I wouldn t bet on it having as much downward thrust as the Atkin tunnel-stern boats. The tunnel-sterns use the entire width of the boat toMessage 2 of 10 , Jan 4, 2008View Source
> I would think the tunnel would force the bowMaybe, but I wouldn't bet on it having as much downward thrust as the
> down in acceleration like on Mr. Whites RM.
Atkin tunnel-stern boats.
The tunnel-sterns use the entire width of the boat to direct the water
downward. By directing so much more water downward, they can use far
less hook in the aft hull bottom than I see in Twinkle's tunnel
section ... and I think the less hook used to direct water downward,
the more fuel efficient the boat will be.
Do you need a tunnel hull for propeller clearance where you're planning
to use the boat?
- The tunnel boat is for the super shallow water we have here. We are in drought level four here in Georgia and the water levels are so low most boats are seeingMessage 3 of 10 , Jan 6, 2008View SourceThe tunnel boat is for the super shallow water we have here. We are in
drought level four here in Georgia and the water levels are so low most
boats are seeing very little use because of the danger to exposed
stumps. This large man made lake is notorious for eating props (even at
high water levels). The shallow draft on Twinkle along with the
efficient four stroke engine might work very nice in these conditions.
I'm not tournament bass fishing so I don't need alot of speed.
I understand about the Rescue Minor's tunnel. In the article on Twinkle
it is mentioned. I have studied all the tunnel boats but like this one
for the simplicity and size.
I'm waiting for Michigan Wheel to get back to me on the prop size.
I'll let everyone know what they recommend.