More Detail on the Micro Repair

My recent post http://rosslillistonewoodenboat.blogspot.com.au/2015/04/micro-repair.html about repairs to a Phil Bolger Micro generated quite a bit of interest, and the following comment from Dave is an example:-

Thanks for the blog post, Ross, but you left out the details on the very parts Id be most interested in seeing!

So if you do a future post on the nitty gritty details of truing up and patching the damage, Id be most interested in that. 

Well, after taking initial photos of the damage, I didn’t many more during the repair process, simply because of time pressure – but here is a brief look at some aspects of the job: -

Initial job was to do a rough paint removal around all of the damaged areas to get a clearer idea of the extent of the damage, and to remove components/timber which had been destroyed. It also allowed ventilation and thorough drying.

Initial job was to do a rough paint removal around all of the damaged areas to get a clearer idea of the extent of the damage, and to remove components/timber which had been destroyed. It also allowed ventilation and thorough drying.

A small puncture wound on the forward/starboard topsides on the outside, and

....the corresponding spot on the inside

Brutal removal of paint, damaged timber, and broken epoxy fillets 

Brutal removal of paint, damaged timber, and broken epoxy fillets

Paint removal from around the forward bulkhead on the interior of the cabin, where the floorboards had punched through.

Most of the work shown above was done using a heat-gun and a variety of sharp scrapers. The paint was all two-part epoxy primer/undercoat and two-part polyurethane topcoat (I know, because I built this particular boat myself fourteen years ago!) and removal was not ever going to be easy. However, the heat-gun and scraper combination is a good choice as long as you are very careful about never overheating the material and damaging epoxy adhesive and paint in locations which are not part of the repair. Other primary tools include chisels, 4" angle grinders, drills, sandpaper - and elbow grease!

Next stage was to carry out a more gentle sanding  using (in this case) a 5" random orbit sander, going down through the grits to about 120 or 180. On the internal areas, the job is more difficult to achieve, and I made heavy use of a Fein Multi-master detail sander and plain, simple sandpaper on a sanding block, or folded triple. Hard work!

See above comments

See above comments

I dont have many photos of the next stage, but it mainly involved pulling usable components back into position using a variety of improvised tools such as lengths of purpose-cut steel angle-iron with holes drilled at strategic locations, and also temporary through-bolts and backing pads. This work can be very satisfying if done properly, and with attention to detail. The key is to have an open mind, and to be prepared to be bold with your surgery.

Once I was happy that my bracing would all work, and that all interfering debris was removed from joints, I opened the whole lot up again, and even spread damaged components further apart (using wedges and chisels etc). With the components held apart, it was relatively easy to treat all surfaces with un-thickened epoxy resin and hardener in order to prime the mating and damaged joints using disposable bristle brushes. This is a very important step if you expect to achieve a good structural repair. With the work area well primed, it was then a matter of applying a rich mix of epoxy/hardener combined with the recommended structural glue/filleting powder additive.

With the structural epoxy  mix worked into all joining areas, I screwed, bolted, or clamped the repaired sections together, which is why the previous work dry-fitting the bracing and jigging was such an important step. Where appropriate, I applied structural epoxy fillets at the same time.

The above two photos show steel angle braces screwed into position over the epoxied repair. In the case of Micro I had the luxury of using straight sections of steel to hold things in place, but on more conventionally shaped boats the same thing can be done using shaped and bent timber splints. Ill show an example of this in an up-coming post on a Whitehall repair.

Interior shot of the repaired bow transom, topside planking, and forward bottom planking. This was taken while the initial epoxy work was still wet and ugly. This work was followed by additional cosmetic epoxy filling.

Exterior shot of the starboard, forward topsides repair taking place. The actual puncture damage is quite a small spot underneath the centre of the plywood pad.

Matching plywood pad on the inner surface of the topside panel. As you can see from the exterior shot above this one, I placed twelve screws through the hull and into the internal plywood pad and pulled them in tightly over the epoxied repair. Note that both pads have been covered in a film of plastic to prevent them being glued to the hull permanently. All of those screw holes had to be repaired later, but the repair turned out well. The plywood pads were large enough to take up the curve of the topside planking when screwed together.

Structural work complete, glass applied where required, fill and cosmetic work done, and the two-part epoxy primer/undercoat applied (the white paint - three or four coats)

Topcoat (two-part polyurethane) applied, with just some minor black line work to be done between the green topsides paint and the off-white bottom paint (that is my little step ladder relected in the paint by the way).

Because of a lack of photos, time and space, this has been a very brief overview of the job, but it may give you some inspiration. Unfortunately, I have no photos of the way I repaired the forward watertight bulkhead of the cabin - a job involving more steel angle bracing and numbers of temporary through-bolts, nuts and fender washers.  In a post in the not too distant future, Ill show the repair of a glued-lapstrake Whitehall tender which suffered very serious damage to her hull in an accident. Most people considered her a write-off, but we were able to give her a new life.

Just a word about repairing screw and bolt holes. Many people simply fill the holes with thickened epoxy and sand the surface smooth after curing. I do not do this because the "cylinder" of hard epoxy in the screw hole intersects the surface of the repair at 90 degrees, and is sure to result in a circular crack in the paint after cycles of expansion and contraction due to temperature changes over time.

My approach is to heavily chamfer the hole on the inside and outside surfaces using a wide countersink or by dishing-out the surface using a sander. Then I fill the hole and the chamfered areas - this gives much less of a stress-riser where the epoxy fill intersects with the surface. However, if the repaired holes are going to be covered with a layer of fabric set in epoxy, this step is not necessary.

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More on External Chine Logs

Phil Bolgers Otter II design, showing her external chine logs

The contributor I referred to in my previous post, Graeme, has written back with with some more comments. I dont want to bore people with an on-going debate, but I think Graemes comment is worth printing: - 

Yes but... Poohsticks is design 10-5-57, ie from the early numbering sytem Bolger used (most of that series originals and other early independent Bolger work destroyed in an unfortunate office fire.) Its almost certain the Poohsticks design was completed in 1957. The date of the write-up about it is not clear to me, but the thinking behind it may well be contemporaneous with its design.

The Light Dory Type V is from the later adopted numbering system, post fire, and denoted as design #265 [there are eight types of Bolger light dory (counting the larger ones #526, #555) as modified from #140 (types -1 to -6) and on; #140-4 being the Orrell famed "Gloucester Gull" version, and #140-6 Paysons "Gloucester Light Dory"].

Dynamite Payson first built a #140-4 in 1967 (Bolger drew #140-6 for Paysons plans sales business much later in the 1970s due to issues with Orrell and proprietry rights. However, what goes around... later, upon Orrells death, Payson successfully purchased all Orrell plan rights, and passed most of the Bolger blueprints/rights back to Bolger!). The Type V, #265, the only one with external chine logs was certainly designed around 1973 specifically for publication in "Small Boats."

Now, to our points of difference: if, as you seem to imply, the 1957 Bolger conjecture (with his obvious caveat) that a chine log "reduces eddying along under the chine by carrying the side flow aft......" is evidence of, as you say, a "Phil Bolger theory that if the hull was properly shaped, an external chine log may reduce drag", then, repectfully, I must disagree for the reasons that follow.

First, in my view its a bit too much of a stretch to turn a Bolger conjecture into a Bolger theory. Bolger raised so many conjectures throughout his career, sometimes with wry humour, often with a caveat as here, yet when he stated his theory in any way he was quite serious, and unreservedly adamant (a good example is at page 50 of "Small Boats" "My flow theory accounts for this...")

Second, sixteen years elapse between Poohsticks and the Light Dory Type V, by which time clearly Bolger is not stating an exterior chine log reduces drag, rather that he merely thinks it may not add to it.

Third, a further nine years later still, in 1982, of the projecting edge of the bottom of Lions Paw #404 ("30-ODD BOATS", p97), which is an excrescence effectively the same as an external chine log, Bolger stated that it "doesnt seem to create much added drag in a hull of these proportions". Unlike Poohsticks, or LDT V, the Lions Paw hull is certainly shaped according to his theory as applicable to sharpies to minimise eddying flow at the chine, ie to minimise drag, yet overall the chine excrescence does result in added drag despite it somewhat fencing cross chine flow (in this design it is tolerated for other reasons).

Fourth, well, admittedly not a reason carrying much weight, but allegedly the LDT Type VI actually is a bit faster than the LDT Type V. There is more going on in the way of design modifications to produce the Type V than just the external chine logs, but perhaps the fact is that they dont help either? (Type VIs have been built with external chine logs too. As far as I know theres been no comparison made with a standard VI.)

best to you
Graeme

interrogate the bolger chart,
every phrase, every mark...

Having read what Graeme has written in this piece and in his previous comment, I have to agree that my statement about Phil Bolger having a theory that external chine logs may reduce drag on a properly designed sharpie hull was overstretching the mark. However, he did imply that the increase in drag, if any, was minor - certainly far less than most people would think intuitively. If you look at my previous post, you will see a list of practical advantages to be gained from using external chine logs.

All of this has been generated by a post I wrote about a Jim Michalak-designed boat. My aim was to inform those people who seem to have a prejudice against external chine logs. Perhaps I was not careful enough with my phrasing, but the practical advantages remain. It is interesting that the people who are horrified by external chine logs dont raise any objections to external keel battens, bilge runners, or lapstrake planking...

Regarding Graemes discussion about dates of design and of publication, I have this quote from a re-publication of the books, "Small Boats" and "The Folding Schooner".

The combination book was called "Bolger Boats" I think (I dont have a copy) and in the preface (Dec 1982) he said, "...What I wrote in these two books, as opposed to what I drew, leaves me fairly contented. Draw you own conclusions from that."

Regardless of the resistance argument, Phil Bolger continued using external chine logs on designs for a very long time.

Birdwatcher with her external chine logs (sorry, I dont have a picture credit and will remove it if anybody is concerned)

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Some more nice plywood

A little good news, some seriously scary shit, and a very impressive trip...

I miss the French canals.

Listening to Soldat Louis

So it goes...

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More photos of Fleet the planing version of Flint

The first example of Fleet, the planing hull version of Flint is getting much closer to launch day. In fact she has already been in the water to allow the marking of the waterline in preparation for the painting of the boot top - empirical data gathering!

Painting has gone ahead at a great rate, using the skills of people who normally apply coatings to aeroplanes and helicopters.

First real opportunity to view the hullform in the flesh.

 The hull shape is similar to the designs of the late William H. Hand, said to have been the inventor of the vee-bottomed motorboat. What made the William Hand designs significant was the way they would handle well at lower speeds when throttled back. Weston Farmer said of them, "They were steerable throughout their entire range of speed in following seas. The full planing boat is a dog in this department. Unless they are banging along full bore, you cannot steer them. And full bore in some seaways with this type of boat, demands Polident for the helmsmans teeth and metal brassiers for the ladies." ("From My Old Boat Shop" International Marine 1979.) Now, I think planing hull design has come some way since Weston Farmer formed his opinion, and there are some very fine designs around for full planing hulls, but the fact remains that for moderate planing and semi-planing speeds, a long, narrow Hand-style hull can be superb.

Getting ready for a trip down to the boat ramp for waterline marking. Gunwales are masked, as they will be finished bright using Deks Olje #1

First splash. Chines dont even touch the water when light. I hope that with a single oarsman on the forward thwart, the boat will be reasonably pleasant to row, even though she is a planing hull. Trim will be everything with passengers aboard.

25 litres of water in the aft well to represent the outboard and fuel, plus two people. The fellow on the helmsmans thwart is quite light, but the trim is very close to that predicted on the plans.

After the floatation tests, marks were made to allow masking-off for the boot-top.

Note the chinagraph pencil marks at the base of the stem.

Boot top masked ready for topside painting

Here you can visualise the fine, sharp lines up forard - she should give a smooth ride at moderate speed in a chop.

Almost ready for the water - just the oiling of the gunwales and breakwater/coaming to go. Test motor will most likely be a 6HP 4-stroke, but that is to be confirmed.

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A new rig for a Goat Island Skiff Spruce for Roger Longs Yawl Dory and more Birdsmouth Masts and Spars

The finished mast and spars delivered and stepped into John Goodmans Goat Island Skiff Yawl #1 in Houston, TX. John does the Texas 200 in a few weeks!

To find good spruce you need to go right to the source. I enjoyed some wonderful walking with a customer who is having a Yawldory by Roger Long, N.A., built and wanted the Spruce for the spars, masts, and oars (my job) to come from her friends land. We walked (i.e., bushwacked) and tagged a few nice Spruce trees.

 

Birdsmouth Masts under construction for a Michael Storer Goat Island Skiff. With Michaels blessing, Clint drew a yawl rig for the boat.

 

Varnishing the Sitka Spruce/Northern White Spruce Birdsmouth mast allows the grain of the Sitka to deepen and develop the contrasting lighter-colored Northern White Spruce. You get some of the benefits of Sitka for half the cost by mixing it with the local spruce we get hear in Maine and Canada.

The two masts are for the Goat Island Skiff, a birdsmouth on the left and a hollow-rectangular mast on the right. The mast on right is a customers that I took in to check for chafing and leathered the chafed areas to prevent more.

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More First Mate Activity

Firstly, thanks very much to everybody who wrote in after the previous post. Im very grateful for the responses, and it helps me a lot in deciding if the information on the blog is relevant to the readership, and gives me some indication about whether I should continue writing the blog.

This week, among other jobs, Ive been preparing materials for the hollow "Birds Mouth" mast for First Mate. The timber I selected is Silver Quandong (Elaeocarpus grandis) which is a light hardwood which grows in the coastal areas of northern New South Wales and in Queensland here in Australia. It is an excellent structural timber for small boat construction, taking both fastenings and glue well, and being suitable for steam-bending. It is the same strength (modulus of elasticity) as Sitka Spruce and is very close to the same weight at 500 kg/cu metre (Sitka Spruce is about 440 Kg/cu metre and Douglas Fir is about 540 kg/cu metre).

The particular stock of Silver Quandong Ive got at the moment is unusually dense, and I was concerned that the mast would end up being too heavy. Once the idea got into my head I started having nightmare thoughts, and before long I had convinced myself it was as heavy as Iron Bark and I was ready to throw away two days worth of cutting and machining! In situations like that, the only thing to do is to carry out a test.

All I did was to accurately cut a piece of the material, measure its volume, weigh it, and then calculate the density. The whole thing took me about three minutes using a piece of scrap from the cutting job. The offcut I had on hand was 125.8mm wide, 19.3mm thick, and I cut it to 250mm in length (the sizes are completely abitrary, but must be measured accurately so you can work out the volume). I weighed it on my workshop scales and it came out at 335 grams.

My sample of timber, with the sizes and weight jotted down in red ball-point

0.250m x 0.1258m x 0.0193m = 0.000606985 cu/metre

0.000606985 cu/m = 335gm = 0.335kg

1 cu/metre = 0.335kg/0.000606985cu/m = 552 kg/cu metre

So I discovered that my timber was actually quite light, being about the same as Douglas Fir (Oregon) and lighter than Hoop Pine. Being a very wet 24 hours, the sample was also damp, so its real density is probably a little lower again. The lesson here is not to get fooled by your insecurities - just do a simple test and many problems disappear. Ive applied this principle to many things like testing plywood bonds, paint adhesion, bending strengths of masts etc etc. I always use basic equipment for my testing, but the results are fine for the work I do.

Here are a few pictures showing the method I use for cutting "Birds Mouth" cut-outs: -

Running a mast stave through the table saw for the first cut. Note that I have a homemade finger-board to hold the stave firmly against the wooden saw fence. Accuracy and consistency are important. These staves for First Mate are 16.3mm thick after having been run through a thicknesser.

I finish the cut using a push-stick for safety

This is how the stave looks after the first cut has been completed

Stave has been end-for-ended and the second cut started

The finished cut

Roller-stands are very useful things to have when working alone with long pieces of timber. Ideally, I would like to have a much larger table-saw, or at least a feed-in and feed-out table, but I have neither the money nor the space. However, it is amazing just how much you can do with cheap, second-hand equipment and a buit of determination

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Whimbrel Two More Questions

Two comments have just come in regarding Whimbrel - one via the comments function and one by email.

First came from Robert: -

Ross- Im following Whimbrel developments with keen interest. I have long considered Jim Michalaks Frolic2 based on Gary Bs Everglades Challenge success with the design. I live 30 minutes from the start of the EC and hope to enter in the near future.

My only concern thus far is the length of the cockpit and cabin floor. Your drawings show the opportunity for one to stretch out in each spot, but I am 6 4" tall. Can you share approximate lengths of those spaces?

The cabin and cockpit arrangement on Whimbrel owes much to the brilliant design concept that Phil Bolger employed in his Micro. By that I refer to the cabin space and the cockpit "overlapping" longitudinally so that a person sitting or lying down at the forward end of the cockpit is actually positioned above the legs of a reclining person in the cuddy-cabin - in much the same way as happens with quarter berths in larger cruisers.

You can see here how the accommodation spaces overlap

The cockpit and cabin space is unusually large for such a short boat, due to the 6 8" beam which is carried well forward because of the pram bow. In fact, there is space aft for a substantial aft deck and associated buoyancy/storage compartment. This aft deck will also allow for the use of a self-draining outboard well similar to the ones Ive used on a number of my other designs.

Periwinkle on launching day showing the self-draining outboard well. The camera had a wide-angle lens making the well look a bit larger than it is in the flesh

Back to Roberts question...

The longitudinal space available in the cockpit, measured between the main bulkhead and the forward bulkhead of the aft deck i.e. the total length of uninterrupted sleeping/sitting space is 6ft 8-9/16". In the cabin, there is 6 6-5/8" of bunk-space with an additional 11-1/8" of clear space between the forward end of the bunk and the forward bulkhead of the cabin giving 7 5-3/4" total. There are compartments leading forward from the end of the cabin for stowage - two accessible from in the cabin, and two from on the deck which drain overboard - used for anchors etc.

Another comment came from Wayne Jorgensen: -

Ross
another quick question re Whimbrels pram bow. Ive spent some time watching Sabots trying to punch into a chop- to the detriment of their speed and handling. Wont there be the same issues with Whimbrels near vertical pram bow? Scandinavian prams lift their bows much higher so this is not really an issue with them but then they are not live aboard cruisers either.
Regards
Wayne

I agonised over this very matter when I was doing the initial hull modelling. The competing factors were;

• maximum volume and reserve buoyancy on a given LOA;
• maximum speed (in smooth water) from a given LOA;
• lack of annoying wavelet noise under the bow while at anchor;
• a chine-line (in body-plan view i.e. viewed from bow and stern) which would produce the minimum cross-flow and eddy-making.

I like the Scandinavian-style pram designs with their bow transom carried high and narrow - you see the same thing on some sampan designs. The problem is that the length of the boat would have to be increased significantly if one was to retain the required shape and buoyancy, just as would be the case with a sharp bow.

It was Phil Bolger who pointed out that a vertical transom gives the maximum waterline length for a given length on deck. He also said that a vertical transom can dig into waves and throw spray - but he then went on to say that by raking the stem forward it would reduce the spray and the digging tendency, but would make the boat longer. So why not pull the waterline length out to match the new length on deck with a vertical transom and get even better performance? Here is one of his several comments on the subject: -

"Raked transoms make a faster boat less badly stopped by waves if they are raked out from the given bottom length, but in that case the boat would be better still if the waterline were carried out to plumb transoms at the new overall length...." (Boats with an Open Mind, International Marine 1994)

What I could say to make myself feel justified is to say that Whimbrel was a 17 boat with a nicely raked bow transom, but I pulled out the bottom length to produce more volume and speed...... But no, I drew what I thought was a good compromise for a fellow who wanted a maximum LOA of 17. The customer went overseas and had to cancel the design, but I was so taken with it by that time that I decided to finish her off as a stock plan. That is why it has taken so long for me to finish, as I only work on the drawings occasionally.

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New kits Old kits More kits!

New and Updated Kits

Calendar Islands Yawl under construction
Updated Deer Isle Koster (KDI) kits being cut out West

The CIY hull#1 is being expertly built in Duluth and everything is looks really good. The boat has been set up and planking has started.

The building jig set up was all CNC cut and self-jigging. In a post on the Wooden Boat Forum about the CIY project, the builder says "I have the distinct sense of the boat building itself" as he assembled the building jig and is not planking within 10 days time working on the side.

Here is the boat so far, all photos courtesy of Jim Levang, builder and owner of hull #1.

The building jig set up. All parts are CNC cut.

The stem, bulkheads, centerboard trunk, and transom all set up. They were all CNC cut.

Bottom and garboards attached!

But thats not all! You can also get the updated KDI. This model is not my own design, but drawn originally by Bruce Elfstrom, friend, fellow designer, and small boat guru from Connecticut who plays with boats, particularly Scandinavian type boats on the side. I have done a lot of new design work with the help of three builders of hull #3, 4, and 5. Photos below courtesy of Frank Stauss in New Jersey. He looks to be doing a fabulous job. 

New Jersey KDI.

NJ KDI.

The Deblois Street Dory is getting a few tweaks to the building jig set up to facilitate building and then two kits will be cut. Finally, the last project will be to finish the Drake 19, a new model. A bit of a line up is forming there for this kit. Everything is on track to be done by the end of May. Then I am going rowing and sailing, dang it!

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More on the Centreboard Shape Issue

Ive been working on the possibility of producing an altered internal layout for both Phoenix III and First Mate, but as always seems to be the case with designs, it is better to go with an entirely different boat, with the desired element designed-in from the start.

Before the flood did its job on us, I had been working privately on a new design for my own use. She was to be the same size as Phoenix III and First Mate but was to be slightly higher in freeboard, have a rectangular centreboard to allow a forward rowing station in addition to the midships thwart, and to be of a shape which is suitable for both glued-lapstrake and strip-planking. The rigs from the original two boats would work, but I wanted to use an un-stayed gaff-headed cat with a small (optional) jib set flying.

This hull shape has less bearing aft than the other two, so it wont be necessary to pay lots of attention to sailing her flat - she should balance quite well at significant angles of heel. In fairness, Phoenix III is pretty good in this regard anyway.

Work was interupted by the floods, but here is a rough drawing for the sake of interest.

The boat is shown with a vertical transom in the drawing, and with five planks of lapstrake or batten-seam (or stitch-and-glue) planking. The final design (if ever finished) might well have a raked transon - say 10 degrees - and would also has a set of lines showing a completely round hull for those who may wish to build strip-planked, cold-moulded?, or lapstrake with a larger number of planks. The cut-away forefoot is to make planking with wide strakes easier.

Dimensions to the inside of the planking are 4610mm/151-1/2" length x 1373mm/46" breadth and a total of 104 sq.ft of sail including the flying jib.

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More about Jims DS15 Project

In a November post I wrote about the Didi Sport 15 that is being built in Port Elizabeth, South Africa, by Jim Foot. Jim has continued to build at a good pace and his boat is moving into the final stages of construction.

Jim has provided a steady stream of photos that document his project through all of its stages. He appears to be doing a very capable build and his boat should be sailing within months.

Jim bought a plywood kit from CKD Boats in Cape Town. It was cut by CNC router using cutting files that we prepared and supplied. Similar kits can also be cut by our other kit suppliers in other countries.

Beautiful standard of hull finish shows off the hull shape.

Internal framing of Jims DS15 hull, CNC-cut by CKD Boats in Cape Town.

Spinnaker pole launch tube

Internal surfaces sealed with 3 coats epoxy

Adding doublers for mainsheet track and epoxy-coating underside of deck.

Jigsaw-jointed cockpit sole installed and cockpit sides being fitted.

Framing of foredeck and cambered mastdeck.

Mastdeck being fitted.

Cockpit and decks nearing completion.

Mound for rudder pintles.

Casting lead keel bulb.

Thanks Jim for your photos and for your enthusiasm. I look forward to the launch and sailing photos of your new boat.

To see our full range of designs, please visit http://dixdesign.com/.

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