Modified Bolger Sharpie

**TerryLL** · 08-27-2011, 08:57 PM

Re: Modified Bolger Sharpie

Something like this maybe?

**Wavewacker** · 08-28-2011, 06:35 AM

Re: Modified Bolger Sharpie

Thanks Terry for your efforts and that is a nice one!

What I was thinking was a vertical side that goes above the water line and then goes to a fuller beam, much in the same way a catamaran hull does on the inside for the cabin, either flairs outward or makes almost a 90 degree transition (L), where that part of the hull below the water line is long and narrow.

The cabin of the one above is about what I had in mind, but much taller for standing headroom much like Bolger's Tennessee.

I like double enders, but for me that's twice the headache, the transom needs a small outboard.

In the 60s there was a Batboat, where the sides had a foil look, my thoughts are not as pronounced or obvious and would begin flair a few inches above the water line.

I like the heavier looking bow stem above, that's a keeper!

**Tom Painter** · 08-28-2011, 06:46 AM

Re: Modified Bolger Sharpie

Originally posted by Wavewacker

Noticed that many tris and cats use extruded or flaired hulls above the water line to increase interior volume. Now, they won't heel like a mono but what happens if you take a Bolger sharpie with 90 degree sides and flair them out above the water line and increase the freeboard some, then attach a cabin with a rounding top.

This would be a very simple and probably under powered sail plan for it's size and used with a small outboard, 10 hp. Hoping for 10 15 knts. cruise

If the flair were a hard 90 degrees out for a few inches this would be a very hard chine, just a few inches, 6 or 8 inches out which would give you a foot or more inside. Let's not picture this yet as I'm sure it could be pretty insulting to the eye. What if we flair it up and out with a nicer looking flair and keep with the shape of the hull forward to midship and bring it back in? Stern to midway where it would disappear.

Has anything been done like that? Is there a design for something similar?

Why? Increase interior volume at a level that could be used for counter space, a few inches for a wider berth, storage above seating...

Secondary stability, alot of secondary stability, keeping the higher cabin and rounded top to be self righting....

A better flair above the water line may have a better effect on the air draft than against flater sides....

And, isn't a curved plane stronger than a flat plane?

Wouldn't this provide more space with less wetted surface area at the hull?

Say LWL of 26 to 32', much like the Bolger Tenn, or Mungoo. but with a more conventional cabin as on a canal cruiser style.

Comments, suggestions, tell me I'm nuts, whatever...

Thanks

Box keel/sponson sharpie

Microtrawler

http://www.duckworksmagazine.com/00/DM1999/articles/microtrawler/index.htm

Bolger did a lot with this both sail & power, beginning with the Gloucester Yawl (in Small Boats) I think.

**Wavewacker** · 08-28-2011, 07:04 AM

Re: Modified Bolger Sharpie

I guess that is what it amounts to! That's it! A much larger box keel. I'll study that some more! I guess what I was thinking was a little taller box, or perhaps another box above......man I wish I could load pics.....

And, as a trawler theme, I like that. I really like the port lights of that one instead of the picture windows, especially the round ports forward. In the event I'm rolled, I want the water kept out for as long as possible with the least damage.
Put a little more curve in that cabin top and that's it!

Thank you, thank you, thank you!

**JimD** · 08-28-2011, 09:23 AM

Re: Modified Bolger Sharpie

Brainstorming can be good but that is a really bad idea.

**Woxbox** · 08-28-2011, 11:43 AM

Re: Modified Bolger Sharpie

Brainstorming can be good but that is a really bad idea.

It's not just adding volume, it's adding weight and what happens when someone stands on the edge of that overhanging deck? Much better put the extra lumber into making a longer boat. Either that, or actually go with a trimaran so you have the stability, too.

**Wavewacker** · 08-28-2011, 07:24 PM

Re: Modified Bolger Sharpie

Yes, this is hard to explain, wish I could post drawings....but, I went through a few hundred pics of boats and there were about ten in that batch that had this basic design. Some were futuristic designs, probably from the 60s, but a few were in the water. Woxbox, I think it would be like standing on the side on my toes with my weight off center getting ready to do a back flip off the boat, I'm talking a few inches, 6 gets me an extra foot of interior room without increasing the hull surface.

I'll see if I can get one of the kids to copy some of those pics and post them.

And Woxbox, I'm really looking hard at the tris for that reason. I like Bolger's Tenn. it has the room, the economy, my only preceived problem is the wave slap and the cabin top, I'd rather have different look to it. I was also wondering about stability in rougher water with the narrow beam and high house, so I thought if there was a little more freeboard and if it kicked out a few inches as I try to describe. In those pics there was a trawler with a similar hard chine, which is closer to what I was hoping for.....

And Woxbox, you have given me alot of advice here and it is appreciated! As you said before, I should probably buy a boat for the big trip and build a small something to get this build stuff out of my system. Seems that sharpie hull is used with tri-hulls, but doing a large one (would be nice) would be a bear to haul around... Thanks again.

Jim, it's been done, why so bad? There should be a balance for the additional weight, I doubt the weight would be much more, it's only a few inches of wood difference, but I'm all ears (actually eyes..).

**James McMullen** · 08-28-2011, 08:21 PM

Re: Modified Bolger Sharpie

wavewacker, if less than ten out of those hundreds of boats had this sort of basic design, then that's almost certain proof that there's something fundamentally wrong with it or at least that the expense and complication aren't at all worth it. There's nothing new under the sun, amigo. Adding a little more free board and kicking the beam out a little bit makes for a whole new design,and you'd better be damn sure you know what you're doing before messing around with proportions casually. Phil Bolger is one of the acknowledged masters of these modern simplified sharpie types, and even he has had his share of failures and very compromised designs with lackluster performance or worse, and he knew a hell of a lot more than us about boat design.

If you don't know how the dish is supposed to work out, you really ought to follow an established and successful recipe unless you've got time and ingredients to waste. Just like with food, the same starting ingredients can be a success or a complete failure depending on the chef, and even with the best of intentions, most of them are no better than average. And the chance of an amateur chef actually doing better than average on the first try is almost non-existent. If you really want a genuinely successful boat, you better not leave anything to chance or just wing it on the design front.

**Woxbox** · 08-28-2011, 09:15 PM

Re: Modified Bolger Sharpie

Wavewacker -- I used to sketch out all sorts of ideas, and I've read countless books and magazine articles about all sorts of designs and design ideas. I used to think for sure I could come up with something a bit better than what was already out there. The whole thing has been an education process for me, one that has stretched over a few decades. The more you understand why boats look as they do, the more you understand why that impulse to just make a nice looking boat a bit wider or a bit taller is just that -- an impulse that's best left to pass. What James says is exactly so -- the professionals really do know what they are doing, and if you want a good boat, buy or build one with a proven record.

I don't know how many times in the past I sketched up an idea thinking that I had something that really was worth building. But in every case, the more I studied it, the more I understood why the professionals were doing things as they were. No regrets, it's a fascinating process for me and a fine pastime.

In fact, being pretty pragmatic about these things, every time I started thinking I'd build a bigger boat, I wound up buying a used one and fixing it up. That's where the value for the money is. Last fall I bought a beat up 27' trimaran. I worked on it all winter and through the spring, and was able to get it in the water this summer. If I'd wanted to build a similar boat, it would have cost twice as much and taken probably four times as long to go sailing. And coincidentally, my budget was the same as the one you suggested in another thread.

**Wavewacker** · 08-29-2011, 05:55 AM

Re: Modified Bolger Sharpie

Thanks guys, I do understand what you're saying and you're probably saving me alot of money! For the bigger boat, I'll look for an existing one to tweek up. I'll consider doing a smaller one that is simple and conforming so I can get some glue on the floor. In fact, I might just fool around with my canoe, put a deck on, set up a sail rig, build the leeboards and slap a rudder on it, I should be able to get the floor dirty with that. Thanks!

**brucehallman** · 08-29-2011, 12:56 PM

Re: Modified Bolger Sharpie

Originally posted by Wavewacker

What I was thinking was a vertical side that goes above the water line and then goes to a fuller beam,...

I think you are describing a "box keel" which Bolger has used on several designs. In essence, the bulk of the buoyancy of the boat is carried in a long lean (square sided-pointy ended) central sponson. Hydro-dynamically this has lots of advantages. Above the waterline, the hull steps out, flares out, etc.. to give better cabin ergonomics. What happens above in the air is of little concern to the water flowing underneath.

**Wavewacker** · 08-29-2011, 02:00 PM

Re: Modified Bolger Sharpie

Yes, that's what I was trying to explain. Come to think of it very few boats do not flair or step out above the water line. Doing so in porportion and balanced is obvious. Keeping with that contour of the bow at the sides and flair out going back. I saw one tri that had a cabin that looked like a larger box sitting on the main hull, but I was not thinking of such extremes. Thanks for you input Bruce.

**brucehallman** · 08-29-2011, 02:31 PM

Re: Modified Bolger Sharpie

It is interesting you ask about box keel sailboats, because I just was reading about Bolger design 680 Nanocruiser, which is built upon the Bolger experimental "Flying Cloud" (design 614, circa 1990), where PCB commissioned a half scale model to water test out the concept. This quote is fascinating:

"First trial showed that the thick box keel was not good enough lateral plane; she sailed, including to windward, but close-hauled there was unacceptable leeway (interesting because a flat keel of the same profile would have held on well.)"

In other words, the lateral plane of the sides of the box keel do not equal the lateral plane of a similar sized flat plate fin keel. (Explain why!?!)

Anyway, in design 680, (not yet built) PBF added a "chine runner" style plate to the bottom of the center portion of the box keel to achieve more grab against leeway.

**brucehallman** · 08-29-2011, 02:36 PM

Re: Modified Bolger Sharpie

The Bolger design "HG Hassler" uses this box keel concept in the extreme.