Bolero Build

Designs for inboard or outboard power

Moderator: BruceDow

nybhh
Posts: 42
Joined: Wed Sep 05, 2018 2:16 pm

Bolero Build

Post by nybhh » Fri Oct 12, 2018 12:44 pm

I’ve chosen the Bolero plans as a starting point towards what I hope will eventually end up similar to the Van Dam Don Don with perhaps a little Riva Iseo and Glen L Gentry DNA thrown into the mix, all in bright mahogany of course. :D

Image

Image

One day in the distant future, I hope to enjoy the boat in the Hudson River from the mid-Hudson Valley down to the New York City harbor and the East River out to the Long Island Sound. The Bolero, with its 20 degree deadrise and over 24” of freeboard should handle these waters nicely. The 23’ Tahoe was a strong contender but as of now, I’ve decided on the Bolero primarily for its stern/v-drive engine configuration and the resulting cockpit layout.

One of the things that has made this choice difficult is the Bolero is one of the most under-represented designs on the forums and as a first-time builder, the lack of support from other builders here was and remains a concern. To partially overcome this and leverage my CAD background, I have decided to document an as-designed virtual build of the Bolero before beginning a modest redesign to modernize it a bit and bring it closer in-line to what I’m looking for. This exercise should also allow me to understand the design intent so any modifications I make will hopefully not adversely affect performance or build viability.

I also hope this will exercise will better document this design for others considering it and perhaps other builders who may choose to tackle a Bolero build one day.

In order to understand as closely as possible how the actual build might go, I’ve chosen to model the boat in a sequence and manner that will attempt to simulate a physical build as much as possible, allowing me to problem-solve as much as possible now before I move to the shop.

I began by having the full-size template (42” x 120”) scanned at 300dpi and then traced all the frames, transom, stem and breasthook in CAD, using faired nurbs curves where applicable. I took care to manually trace these extremely carefully and set an accuracy threshold of ½ the width of the “pencil” line which were literally about 5-6 pixels wide at that resolution.

I modeled the frames “flat” and then positioned them in 3D space snapping them into a pre-drawn grid of offset lines representing frame spacing, the setup level, designed water level, etc. The computer affords a level of precision I can only dream about in the shop and a curve that is 1/16” out of fair can be easily detected. I did make a decision to model the hull right-side up rather than the typical flipped configuration everyone is used to seeing however.

Image
Image
Image
Image

The Bolero plans lists frame #1 as the aft-most frame forward of the transom while the forward most frame is #8. The full-size templates for this design only show the inside face of the hull sheathing so there are a lot of offsets and head scratching to even get to the full frame profiles and I’ve already made a few mistakes I’ll detail later that would have resulted in firewood if I weren’t mocking everything up in the computer first.
I began lofting the chine logs and sheers last night and ran into some issues forward of frame 5. I’m going to track down exactly what’s going on will probably post a follow-up later this weekend or early next week. You can see the issue slightly in the following images where the sheer dips at frame 6:

Image
Image
Image

I had an enormous amount of respect for the builders on this forum prior to beginning this exercise and can say it has already increased ten-fold since I began modeling this boat and I already fear "real world" fairing that 2.25” stem and the rest of the longitudinals I’m modeling now!
Last edited by nybhh on Sat Nov 10, 2018 5:55 pm, edited 2 times in total.
-Brandon

TomB
Posts: 337
Joined: Wed Jan 18, 2017 4:07 pm
Location: Holland, MI

Re: Bolero Build

Post by TomB » Fri Oct 12, 2018 1:38 pm

B,

I am excited for you, great choice!

You model is coming along really nicely. I see your point about frame 5,6,7 and a little hiccup in the sheer. An inch here or there, or a degree off...should be an inexpensive fix :D :D A top view may help narrow your search for the fix.

When I think about fairing, I try to remember which edge of the frame is depicted on the template, ie, for frame 1 it is the forward edge and should still be there after fairing, for frame 8 the aft edge is there after fairing. As you model the longitudinals are you able to attach them to the appropriate frame edges and allow them to notch fully into the frames as needed?


Tom

nybhh
Posts: 42
Joined: Wed Sep 05, 2018 2:16 pm

Re: Bolero Build

Post by nybhh » Fri Oct 12, 2018 2:15 pm

Hi Tom, it's a pretty cool design and I hope I can give it a little more exposure even if I ultimately go another way.

I'm pretty sure the out-of-fair issue is a height problem on frame 6. It looks fine in plan. I'm going to recheck my setup one last time over the weekend but I'm beginning to think the error may be a reproduction/scan anomaly as it also shows up in my lofts of the raw sheathing profile curves without any frame modeling or anything requiring my interpretation/errors other than setup.

I'm not sure if all the designs are this way but the Bolero only provides an inside hull profile so all the frames, notches and even the bottom frame profiles have to be offset from the template curves to allow for the bottom battens since this is a "floating" frame. The hull only contacts the frame between the chine and sheer. There is a lot of opportunity for error in arriving at those frame profiles but that dip is showing up before all of that. I'll get to the bottom of it.

Regarding your snap question, I'm using Rhino 3D and "point" nurbs rather thans CV nurbs so I can force the curves to pass through a specific point on the frame. I knew that dip was there so I just quickly lofted the sheers last night so I could see them in an actual render rather than just the viewport. I will need to go back and redo the lofts much more carefully when I get that frame resolved and taper the frame notches accordingly. The frames are currently just raw extrusions on the "high" side so they would require filling if I had pre-cut the notches on a physical build that way.

I'm really curious now to compare these plans to some of the others. There may be a reason there are so few Bolero's out in the wild :D

-Brandon
-Brandon

User avatar
kens
Posts: 4579
Joined: Wed Nov 12, 2003 5:25 pm
Location: Coastal Georgia

Re: Bolero Build

Post by kens » Fri Oct 12, 2018 2:58 pm

Hi, glad to see someone build one of the 'go-fasts'. The majority of builds here are the small outboards & the tumblehome mahogany runabouts, yes the Bolero and other of the 'cigarette style' are not well represented. They have been built, but just not as many as the others, there are pictures in the archives section, have you been to that portion of the webpage?

When you mention that you are 'lofting' this, I must ask why? If you already got the plans, then why loft it? Just build it.....

then you mention that you would have a lot of firewood, again I must ask why?
To the best of my knowledge, Mr. Glen L. did build one example of each of his drawings, so that begs me to ask about the firewood thing?

If I may ask, does the Bolero plans swap the stations fairing (fore & aft sides) looking from mid-frame? (mid-frame being frame 4)?
Oak is over rated, everything about it takes extra time; then it warps, splits or checks !!! :roll:

TomB
Posts: 337
Joined: Wed Jan 18, 2017 4:07 pm
Location: Holland, MI

Re: Bolero Build

Post by TomB » Fri Oct 12, 2018 3:13 pm

Brandon,
I'm not sure if all the designs are this way but the Bolero only provides an inside hull profile so all the frames, notches and even the bottom frame profiles have to be offset from the template curves to allow for the bottom battens since this is a "floating" frame. The hull only contacts the frame between the chine and sheer.
The three sets of plans I've seen are all similar to each other (less than one percent). The template drawing gives a setup line, centerline, and frame and transom profile. Frame width/thickness are covered by notes. Longitudinals are notched into the frames along with limbers on the bottom. Bottom planking is in contact with keel, frames, and battens. A few of the builds have bottom battens riding over the frames with the bottom planking only touching the battens and not the frames. Is that how the Bolero is designed, bottom planking only touching the battens and not the frames?

Tom

nybhh
Posts: 42
Joined: Wed Sep 05, 2018 2:16 pm

Re: Bolero Build

Post by nybhh » Fri Oct 12, 2018 4:04 pm

Tom,
Yes, that’s right. The bottom battens float over the frames and the bottom planking only touches the battens, keel and chine logs but ONLY at frames 1-7. The bottom planking does attach directly to frame 8 since some of your battens have stopped by then. The side planking does however touch the frames so this results in some confusing chine notches that negotiate that condition, especiIally at frames 7 & 8 that are single piece frames. You only get a “planking profile” and not technically a frame profile so the frames take some interpretation since they are offset from the planking profile in areas.

Kens,
See above for the firewood making! Since computer mistakes are cheap, I jumped in much quicker than I would have otherwise but I honestly don’t know when I would have caught it in the shop. It only became obvious when I started lofting the chines that I had screwed up the notches at #7 and #8.

When I used the term lofting above, I was referring to the technical term of modeling geometry through a series of curves which is also called lofting. Sort of the “bending wood around the frames” in the computer, not lofting the hull from offset tables.

If you meant, “why the hell are you modeling and not building!”, also a good - and complex question. I guess my main response would be that I am not fully committed to this design yet. I also love the classic tumblehome runabouts but the hull designs and cockpit layouts aren’t ideal for my needs. I’m going to try and arrive at a design on this hull that has some of those classic elements we all love and I referred to in the begining of the first post that hopefully doesn’t look like a Frankenstein chimera. It is easier and cheaper to test in the computer and if I can’t achieve something I like there, I’ll probably just build a stretched Tahoe 23. I also have a new outbuilding in the works that will fit a 25’ boat where my current garage shop won’t. IE, I’ve got some time to kill!

I don’t fully comprehend your final question but I am happy to answer if I can.
-Brandon

User avatar
kens
Posts: 4579
Joined: Wed Nov 12, 2003 5:25 pm
Location: Coastal Georgia

Re: Bolero Build

Post by kens » Fri Oct 12, 2018 5:22 pm

Well, one thing I have found out, is that you can get different amount of curves, depending on the type of wood you are bending around the chines & sheers.
Example: the sheers up front have the most amount of curve in them, therefore, if you bend a solid piece of oak, vs a laminate of layers of mahogany, you can land on all the lofting frames, but you can get a different curve.

how does the computer know this???
Oak is over rated, everything about it takes extra time; then it warps, splits or checks !!! :roll:

nybhh
Posts: 42
Joined: Wed Sep 05, 2018 2:16 pm

Re: Bolero Build

Post by nybhh » Fri Oct 12, 2018 8:27 pm

Kens,
Thanks for your questions. As to the one earlier, I revisited the plans tonight and your are correct in the fairing drawing, frames 0-3 are on one side and 4-8 (with a 1/2 station forward of station 8 ) on the other, looking aft.

The computer does not “know” when your particular species of wood will fail or the specific characteristics of different materials, at least the software I am using. There is however a mathematically “fairest” curve through a series of points and the NURBS curves in this software is used by naval architects (I’m not one) and are designed to follow that "fairest path". In the case of the Bolero chine logs, provided my frames are modeled and position properly, that point is actually about 4” in front of the stem at the height I have them. I took that position and moved it back to the nearest point on the stem as that should be the both the fairest as easiest to build. If I change a point on frame 7 for example, the curve will automatically adjust within it's adjacent anchor points to find the fairest path. They're pretty cool but the math behind them is over my head.
-Brandon

User avatar
hoodman
Posts: 1880
Joined: Thu Nov 10, 2011 8:48 am
Location: Lafayette, IN

Re: Bolero Build

Post by hoodman » Fri Oct 12, 2018 9:39 pm

I checked out that Van Dam boat you mentioned in your first post. Looks very similar to the Bolero to me. You just need some tumblehome in the transom and you'll be really close. The Bolero is capable of some serious speed. The "floating" frames is part of that. It's a really solid design and you'll likely still be comfy in much lumpier water than a lot of the other designs. It's obviously possible to build as there are examples on the site. I suspect not many have been built due to the style not being as popular. But you can do whatever you want with the topsides. Veneer the whole thing and finish it bright. Change the transom like you want and it will look totally different. Plus it's got bunks so you can spend the night. It will be a really fun way to burn a lot of gasoline.
Matt

Building a Geronimo......!
viewtopic.php?f=2&t=25139

nybhh
Posts: 42
Joined: Wed Sep 05, 2018 2:16 pm

Re: Bolero Build

Post by nybhh » Sat Oct 13, 2018 6:43 am

Ha, it is definitely one of those "gallons per mile" sort of toys. I have to admit I've already started browsing around for engines even though that is so far in the future I'll probably be deciding between battery types rather than gas vs diesel!
-Brandon

User avatar
hoodman
Posts: 1880
Joined: Thu Nov 10, 2011 8:48 am
Location: Lafayette, IN

Re: Bolero Build

Post by hoodman » Sat Oct 13, 2018 6:56 am

Now that you mention it diesel power could be a really smart move. Just talk to Bill E.
Matt

Building a Geronimo......!
viewtopic.php?f=2&t=25139

Denon Osterman
Posts: 515
Joined: Thu Jun 22, 2006 8:58 am
Location: toronto, CAN

Re: Bolero Build

Post by Denon Osterman » Mon Oct 15, 2018 6:22 pm

I really, really, *really* like the bolero. I was almost going to build one myself, but went with the rampage instead. Can't wait to see how this progresses - remember that everything below the waterline should stay as is, but everything above is free game. I modified my rampage somewhat significantly above the waterline to make it slightly less "low profile", as I wanted a bit more free-board and room for everyone - and enough space to comfortably seat six.

A slightly more classic look with some mahogany bright-work would be *gorgeous* - and a great place to stick a 572 with a racing outdrive ;)

nybhh
Posts: 42
Joined: Wed Sep 05, 2018 2:16 pm

Re: Bolero Build

Post by nybhh » Tue Oct 16, 2018 7:04 am

Thanks Denon. I'm watching your build closely as well since there are many similarities between these boats that differ from many of the other builds on the forums. I really like what you've done with it and I'm taking some inspiration from your work!

As for the sheer fairing issue, I basically brought the raw "curves" in from the full-size template tracing and lined them up along my station offsets. This was to eliminate any issues or errors that may have arisen from my frame profiles. Remember these lines represent the INSIDE face of the hull sheathing and those lines are shown in blue. The longitudinals are 3-degree nurbs curves (also drawn in blue) that are snapped to the sheer and chine lines represented in the profile curves.

Image
Image
Image

The software I'm using has some curve analysis tools and I ran a "re-fairing" command on the sheer line and the results of that are shown in yellow. The red lines basically connect the original to the re-faired lines but are in the same fore-aft plane as the profile/station curves. The red basically represents my out-of-fair amount and both of those red lines are right around 2/10 of an inch. That is station 5 & 6 with the red lines.

I've triple rechecked my tracing and setup so the only conclusions I can come up with as to the source of the errors are reproduction/scan anomalies. The full-size templates for the Bolero came on one 42" wide x 120" long piece of paper, folded. The curves are also drawn with 0-5 on one side of the centerline and curves 6,7,8 mirrored on the other side of the center line so the two sheer lines between curve 5 and 6 are almost 8' apart on a piece of folded paper that got sent through a large-format scanner. I have full confidence that these out-of fair issues were not present in Mr. Witt's original design so I'm going to chalk it up to reproduction errors which is entirely reasonable and probably not be unexpected.

If I were in the shop at this point, I think a lot of filling, planing and sanding could resolve this but I'd really appreciate feedback on how others would address a problem like this at this point in the build. Because the hulls are usually build upside down, I suspect an issue like this often may not reveal itself until after the flip.

Anyway, because as Tom pointed out above, tweaking my frames in the computer is "cheap" compared to creating more firewood in the shop, I'm going to redraw my frame profiles around a refaired sheer line and work backwards off of that. It is likely that I will mill my frames on a CNC router so I want to eliminate anything now that may find itself in my final design down the road.

EDIT: Now that I'm looking closely at those images, I can also see a little funkiness at 5 & 6 in the chine lines as well. I'm sure I'm going to end up re-fairing both sets of longitudinals and redraw all my frames off of those lines. Sometimes the precision of the computer breeds a sort of, I don't know... OCD maybe?
-Brandon

TomB
Posts: 337
Joined: Wed Jan 18, 2017 4:07 pm
Location: Holland, MI

Re: Bolero Build

Post by TomB » Tue Oct 16, 2018 8:21 am

Brandon,

Two tenths would be difficult to spot upside down at your shoe tops. To fix it if you found it, you would add a quarter inch lamination to the outside of the frame and fair off the surplus and move on, aside from the time it is a cheap fix and invisible when done. In a 24' boat with an 8' beam you got a lot of precision goin' on.

My experience with copy errors is that they are consistent, the whole drawing stretches, twists, or whatever, not just in one area. You mention that the profiles have been confirmed. Have the stationing and nurb attachment points also been confirmed? On my build the stations are 24”, so from the front edge of frame #1 to the front edge of frame #2 is 24”. It goes like that most of the way…until it doesn’t. There is one frame that is 24” between the front edge and the back edge of the next frame. Miss it and you get about two tenths. Attaching the nurbs to the wrong edge of the frame (3/4” to far forward or aft) would also be about two tenths. On Bolero the nurbs would attach at the forward edges of the aft frames, maybe the middle of frame #5, and on the aft edge of the forward frames. If that’s all good then its definitely a copy error.

Tom

PeterG
Posts: 572
Joined: Mon Dec 03, 2007 7:08 am
Location: Connecticut

Re: Bolero Build

Post by PeterG » Tue Oct 16, 2018 10:22 am

An error in the full size patterns is not that uncommon, it happened with my Malahini. The patterns were reproduced slightly undersize on two of the three sheets (1/8" shorter heights and 1/8" narrower half-breadths) and the pattern for the stem had a slightly off curvature that made the stem 3/8" shorter than is was supposed to be. That all would have caused some out-of-fair conditions for the sheers and chines. The drawing sheets for the boat are so well marked with dimensions such that I drew the frames, stem and transom full sized on sheets of plywood using battens. From there I made full size templates of the pieces. The plywood with the drawn frames also doubled as the assembly fixture. Check your drawing for the major frame dimensions, if they are there, I would trust them more than the patterns. I have a set of Key Largo plans that don't give as much info as the Malahini plans, it seems you're supposed to rely on the full size patterns.
Murphy's Law: Anything that can go wrong, will go wrong.
Griffin's Law: Murphy was an optimist.

Post Reply

Return to “Power Boats”