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Rdubs

Spindrift 10N help needed - outboard pad and fwd bulkhead question

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For a small engine, you don't need much by way of a pad, so bulk the area up so it's 3/4" (total thickness) or more and call it a day. The area under the outboard screws and clamp will tend to get beaten up, so consider using a Forstner bit and drilling a shallow, flat bottom hole. Fill this will heavily thickened epoxy (silica and milled fibers). Place these holes under the clamp and screw heads, so they serve as a bearing area, tougher than the surrounding plywood (chamfer or countersink the holes slightly for a better "bushing"). Some outboard clamps have little ridges on them, to help hold them in place. If this is the case, cast the impression of these ridges into the shallow epoxy holes. I do this regularly and simply place a piece of plastic packaging tape over the outboard clamp, before I lightly clamp the engine in place. I backfill the holes from the other side. This leaves a form fitting dent, where these ridges and and the motor fit perfectly. Conversely, you can take a grinder to these ridges, so the clamp lands on the transom flat, eliminating the need to make custom matching dents (you might get a new engine, etc.). FWIW . . .

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Thanks for the input everyone.  I think I wasn't clear...where I'm having trouble is that centerline 1/4" hole which holds the two halves together.  I think there is a small amount of water seeping through that bolt hole.  Tested the dink in my pool and over the course of hours some water would materialize in the rear aft section.  I think part of it may be my washer isn't fully seating due to the fiberglass seams I put in, so I can sand those down more level.  But is there a best practice on how to increase the watertight-ness of the bulkhead mating bolt holes?  I'm thinking just put some caulk in the hole and around the bolt before tightening down, then tighten, let it sit/dry, then when I remove the bolt the clearance around the bolt shaft will be a lot tighter.

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Make an "O" ring from 3M-5200, to live under the washers for the bolts, using thick tape, like a few layers of duct tape. Cut into a ring around the washer landing area, smear in some 3M-5200, troweling it level and let this cure (several days). The bolts will put it in compression and it makes an effective, disassemblable seal.

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Very helpful thanks PAR.

Other closeout item: What is a good placement for cleats, and the size of cleats?  6" cleats look like they would work for holding dock lines without being too tiny.  I imagine good places would be at the aft end on either side, but should you try to bolt them into the gunwale or the quarter piece at the back corner?  For the bow, is it better to have just one on the centerline (I guess bolted into the breast piece), or one on either side of the bow, or none at all since the eye towing U-bolt could be used to take the place of the bow cleats?  

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Gents - quick question.  What's the best practice regarding making the dinghy able to be towed?  The plans looks like you just drill a hole right above the front seat deck and run the toe line through that.   Other pictures I have seen have used a full metal tow eye, mounted further down (about halfway down the length of the bow).  I will probably use the dink towed behind the mothership carrying one or two kids for fun.  

Thanks,

'Dubs

Edit: also, what effect does height placement of the tow eye have?  It would seem that placing the eye lower would raise the angle at which he boat is towed, but too much angle would bury the stern in the water and probably cause a lot of drag.  

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Dubs,

 

Graham swears by a 7/16" hole through a re-inforced block in the bow above the foredeck for a 3/8" painter.  The plans show the block beveled to match the angle of the bow.  You reinforce with 6 pieces of fiberglass tape that extend to 3" on either side of the bow.  

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A lower towing point will usually result in less wandering of the dinghy under tow.  If you've got a bow eye for trailering that will probably be the best point for towing, too.

Having said that, if Graham has recommended a deck-level painter for towing, listen to his advice instead of mine.  He's towed dinghies a lot farther than I have.

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My transition to the current painter/ bow connection design came about because I wanted to avoid a metal eye on the bow of the tender that could attack my boat. I also wanted to avoid a potential leak into the forward flotation compartment. Imagine how it would tow with the bow full of water. I Know that the pundits call for the tow point to be as low as possible. I always use a painter that floats so that it is always lighter than polyester or nylon, especially when wet. This creates a very small catenary when it is towing so that when the tender is eased back to the optimum towing length for the conditions, there is very little change of angle between the low towing eye and where I put it and the conventional position. You need a floating painter so that it cannot get wrapped around the prop.

 

I have experimented with different towing eye heights and I cannot tell the difference. Remember that with the shorter waterline length of the tender she will squat, giving a bow up attitude when the towing vessel is reaching hull speed.

 

Living aboard and using the tender every day except when on a passage, I noticed that after 5 years that there was some wear on the painter where it passed through the bow. I  untied the stopper knot and cut off 6" and after retying it I had another 5 years before I needed to do it again. I believe that a metal connection would need replacing by then.

 

After 15 years of full time use I believe that this method met requirements of being functional, reliable and cheap. If you want to go with the conventional bow eye, have at it, it is a small deal.

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Cantenary, schmantenary.  Keep the eye low, and it cannot "attack" your mother ship.  And no matter how high that dink painter floats, prop wash will suck it nicely into your outboard's rotational devices.  You just need to rely on remembering to getting your dink on a short leash for all those end-of-day maneuvers.  Just sayin'.  

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I was a skeptic of the bowline attached with a knot as shown i the manual. Not anymore. It works awesome and has held up well.

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I glued a short piece of sched 80 PVC through the bow above the deck.  The painter runs through that and is retained with a figure of eight knot.  It makes it easy to raise and lower an anchor for fishing.  I don't tow but this has been very secure for trailering.

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Oops!  I didn't realize I was joking with the Designer, with my "cantenary, schmantenary" wisecrack.  Please ignore my comment, since he has a wee bit more experience in this regard than me.  Apologies, Graham!

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Don,

 

I thought that you came on a bit aggressive for a polite conversation between friends. I accept and appreciate your apology.

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A damn shallow catenary Graham . . . likely much like the grin brought to Dons' face when he realized . . .

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Hey all, thought would provide an update.  Unfortunately, I didn't see Graham's response until after I had already installed the bow eye.  When I didn't get a response I figured all the pictures of dinghys with bow eyes was giving me a clue.  Too late now, but I read a few stories of a dinghy being towed coming up on the mothership from a wave so Graham's method of avoiding a bow eye is pretty smart. 

 

I had previously mentioned a concern about water leaking in through the holes for the mating bulkhead bolts.  PAR have a great idea to create a gasket donut on the washers.  I modified that a little and just used 3M 4200 to glue the washers right on top of their holes, using a thick bead.  That wat the washers are always mounted and I only need to collect bolts and nuts when disassemble, but also the 4200 should stay a little flexible and when the bolts are tightened down, the compression of the gasket will seal off the shaft.  Will get the boat in the water and test it out but for right now, thanks PAR for that great idea.  

 

I ended ded up using that polyeurethane-fortified paint from Lowes for like $25/gallon.  Used about 2/3 of it to put two coats on.  I didn't use a primer just to see if I would need one, I just scuffed up the epoxy surface coating.  The paint definitely stuck to the epoxy, but it comes off pretty easy.  If I move or scrap something up against the hull, the white paint will come right off.  So there's a data point for anyone considering skipping the primer.  Looks great as long as nothing scrapes up against the boat, then you'll be doing touch-up.  

 

'Dubs

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On 7/10/2017 at 0:08 PM, Steve W said:

I was a skeptic of the bowline attached with a knot as shown i the manual. Not anymore. It works awesome and has held up well.

 

I used the hole in the stem for the bow painter of my Spindrift.  After hundreds of cruising miles towing it and never having to worry about being rammed by the eye I would never consider anything else.  I use holes in the transom knees for the traveler and dock lines.  I'm a huge KISS fan.

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A quick drawing of the bonding technique I use on weather decks, hardware attachments, etc. This is an old trick and includes three separate elements. The first most know, which is to bond fastener holes with epoxy. Just drill a hole, fill with thickened goo, then redrill for the fastener. Taking this one step further, you counter sink the top of the oversize hole used for bonding. If used alone, it places a hard plastic barrier under the fastener head and washer if used. This hardened hole top serves as a bearing surface for the fastener head, instead of surrounding wood. Last is to countersink the now bonded hole and fill this area with caulk as you install the fastener. As the fastener starts to crush the caulk out of the hole, it gets trapped in the countersink, pushing against the sides and forming an "O" ring sort of gasket. I learned this back in the early '80's from a guy now long dead, who knew his stuff.

BYYB-408.thumb.jpg.5cd8163caa691dff8aa54e7f2d149994.jpg

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