I would go with a short, angled, sacrificial bow section.
Strong enough to lift the bow if it hits a low obstruction, but which will
absorb the impact by crushing if it hits something too high to lift over, so in
profile, a plumb bow to about 150 or 200mm above LWL, then angled back
about 45 degrees, moderately heavy lay-up on the bottom edge. You could
even rake backwards above the ramped bit for a semi-retro ram bow look if that
blows your hair back. YMMV Cheers,
Peter
----- Original Message -----From: Gardner PomperSent: Tuesday, April 23, 2013 1:34 PMSubject: Re: [harryproa] Logs under bow
Roger,I have been having the same discussion with Rob on my design. We keep going back and forth and I still don't understand. I am with Doug on the idea that a sloped bow would tend to ride up on top of a log and avoid any structural damage. Why is it preferable to crush part of the bow and have to haul the boat out and rebuild it? Is there some disadvantage to angling the bow back a foot or so? the harrys have such a small draft and fine bow that you would lose practically no buoyancy.- GardnerOn Tue, Apr 23, 2013 at 6:24 AM, Roger L <rogerlov@ix.netcom.com> wrote:
"And on another matter, I was reading in Cruising Helmsman magazine about looking out for floating submerged logs around PNG/Indo.
This would be a worry on harrys. Perhaps an extra foot of bow that angles up to take the hit and ride up over the top of the log?"In the PNW (USA) and in the big channels and rivers everywhere it seems that submerged logs are a problem. You hear of boats hitting logs squarely, riding over, and losing daggerboard or rudder or prop or everything.So is an angled bow an advantage or maybe not? And how much of that depends on the angle of the log?I've hit a few logs myself and most of the time the boat moves over a little and the log also moves over and what you have is just a sudden stop and big scrapes down the sides of the hull. The sudden stop can be worse than the scrapes. The only time I had any damage other than scrapes was when I hit a log almost squarely while motoring in my small tri and it took off the prop and bent the shaft as we rode over.My own preference is for a straight bow with the forward foot or two being made to crush and easily replaced. That puts the actual structural hull a foot or two behind the crush bow.Obviously there's an advantage if pieces protruding beneath the hull are able to pivot. If that can't happen, I'd prefer things to break away cleanly in a manner of my choosing. Makes repairs easier.Roger L.....................
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