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Author Topic:   Where to put the waterline on a 67 Nauset with 90hp Yamaha
Soho posted 08-06-2001 10:40 PM ET (US)   Profile for Soho   Send Email to Soho  
One of my current dilemas is where to put the waterline on my 67 Nauset when I finally get her back overboard. ( soon I hope ) Now, I did measure where it was before removing all the old paint - in the process of painting entire boat- but I cannot remember exactly how the old waterline looked when the boat was in the water - she has not been in for about 3.5 years.

As noted, the boat is a 67 Nauset with a new 90 Yamaha to go on it. No real extra weight to speak of in the stern as the battery and 12 gallon fuel tank are in the homebuilt console.

Can anybody offer any input as to where they might place the WL - starting height at stern and finishing point where it will tuck under to the bow...

The old measurements that I have were that the top of the line was 12" from the botton of the gunwale at the stern and 15" under 10' up the boat - really scientific as you can see. I do not have a trailer so just dropping the boat to measure in is not the easiest option, although I guess I could do that as it comes back from having the new engine installed...

At any rate, any input would be appreciated.

Thanks in advance.


Soho posted 08-06-2001 10:42 PM ET (US)     Profile for Soho  Send Email to Soho     
Opps, probably should have put this under the Repairs section ! Sorry !
Chesapeake posted 08-06-2001 11:09 PM ET (US)     Profile for Chesapeake  Send Email to Chesapeake     
Soho: I am due to get my '69 Nauset back from 90 yam install this Friday and will take it on vacation to Wisconsin's north woods to break it in. (Larry Goltz won't believe that Chesapeake is finally in the water here in Chicago!) I could take a picture, if you'd like, of what mine looks like in the water (she is bottom painted). I could then give you the critical measurements for my bottom paint and you can decide for yourself on that basis

I won't be able to get back to you until the 21st or so. If that will be helpful, let me know.


Bob (Chesapeake)

triblet posted 08-06-2001 11:11 PM ET (US)     Profile for triblet  Send Email to triblet     
Uh, put it in the water, mark it, pull it
out, dry it, paint it.

BTW, someone had a great idea to use a laser
level to mark the precise line so it's truely
level on that compound curve.


Soho posted 08-06-2001 11:15 PM ET (US)     Profile for Soho  Send Email to Soho     

Thanks for the offer; pictures and details would be most helpful for fine tuning. The 21st should be no problem for me in terms of timing, as I am not quite ready to launch.

Thank you again,


Soho posted 08-06-2001 11:38 PM ET (US)     Profile for Soho  Send Email to Soho     

I hear you, as I wrote the message I realised that I could probably have them drop her in on the way back from the engine mounting... for the extra 50 bucks it is probably worth it to get it right. Just that as I am paying for each haul on a trailer, I was trying to minimise the trips. Of course after the work and cost to date ... the extra 50 skins is a drop in the bucket !



lhg posted 08-07-2001 12:32 AM ET (US)     Profile for lhg    
I have the BW Owners Manual for the original 16' hull (pre 1976) and although a picture is worth a 1000 words, here are the dimensions for bottom paint.

Envision the hull upside down: beginning at the transom, the waterline crosses the transom in a straight line from chine to chine. The chine is the last little lip on the hull bottom before it turns up the side of the boat.

Moving forward of the transom, the waterline extends along the chine line for 96". The bottom paint DOES NOT go on the straight vertical sides of the hull!!!! But it does cover the horizontal edge of the chine line.

The following dimensions are all from the center of the bow, MEASURED HORIZONTALLY, not along the hull: On the bottom point of the angled-in hull line (basically the edge where the sloping side of the hull and underside of the hull meet, mark a spot 45" from the bow. Connect a straight line from the prior 96" spot to this spot. This is how the waterline crosses the angled-in bow chine surface. Mark a spot on the rounded keel centerline 33" from the bow. (dimension should be on the horizontal axis, and NOT along the bow contour). Finally, mark a spot in the center of each hull hollow 57" from bow, also measuring horizontally, not along the slope. Now, from the pointed hard chine edge (45") to the hollow (57") to the keel (33") a curving "W" is drawn, connecting the "dots". In a drawing, the outside legs of the "W" are shorter than the center upside down V portion. (the ouside legs are 45" from the bow, while the center of the "W" is only 33" from the bow. This waterline will cross right over the side splash rails on the bottom.

I know this may be a little hard to follow, but if you sketch out the approximate shape of the upside down hull bottom, it will make sense. These are Whaler's dimensions, not mine. Good luck.

Whalerdan posted 08-07-2001 08:10 AM ET (US)     Profile for Whalerdan  Send Email to Whalerdan     
Soho - Be careful using Chesapeakes numbers and picture as (if I'm not mistaken) he will be using this in fresh water and (again if I'm not mistaken) you'll be in salt. I know this will make somewhat of a difference but I'm not sure how much.
Soho posted 08-07-2001 08:38 AM ET (US)     Profile for Soho  Send Email to Soho     

Thanks for the detailed description. In fact the hull is upside down at present so following what you have described should be pretty straightforward ! I will give it a shot when I get home tonight. I think that I may have to provide some small allowance on the WL for the boat being a little heavier now then when originally launched but what you have provided is great to provide the baseline to work from.

Whalerdan: good point on the saltwater, [ you are right I am in saltwater ] I will try to factor that it as well.

I will let you know how it turns out.



andygere posted 08-08-2001 05:33 PM ET (US)     Profile for andygere  Send Email to andygere     
I'm going to launch and mark my Montauk this weekend. It will be interesting to see how close my waterline is to the one shown in the owners manual.
mattr posted 08-08-2001 07:34 PM ET (US)     Profile for mattr  Send Email to mattr     
Not to add too much confusion here, but I remember reading about a method to mark the waterline. Get a two foot section of clear tubing - an inch or so in diameter. Plug one end and fill halfway with water. Put your thumb over the open end, and bend the tube in the shape of a U. Then, where the water settles on one side of the U, run that along the hull with a pencil - the water will always find the natural level point...

Sounds sort of wacky, but I remember reading about it somewhere...


Chesapeake posted 08-08-2001 09:03 PM ET (US)     Profile for Chesapeake  Send Email to Chesapeake     

Having heard Larry's post, that is an eye-popper to me. My paint extends up (and inappropriately) onto about 3 inches of the straight vertical sides of the hull.

I will still be happy to send you a pic, but obviously, dynamic testing plus BWs recomendations may yield a better end product.



Soho posted 08-09-2001 07:53 AM ET (US)     Profile for Soho  Send Email to Soho     

Actually, I checked out a Montauk here that is a similar vintage ( I think ) and really she does not sit much lower in the water then the WL described by Larry; maybe about 1 inch up the side of the boat at the stern. Now, he has a 90 Yamaha on it as I will have and his weight distribution looks to be a little more stern oriented then I will be ---> my conclusion is that if I went about 1 inch up the side it would be fine. Probably run that to the crossover that Larry describes about 96 ' up the hull. Any photos that anybody has are welcome for reference.



andygere posted 08-13-2001 01:25 PM ET (US)     Profile for andygere  Send Email to andygere     
The waterline on my Montauk in saltwater is about 3/4" above the chine in the stern, and right at the chine at the inflection point. This is with both 12 gallon tanks full, a six gallon tank sitting in front of the conole, dual batteries in the stern, and 1979 85 hp and 15 hp motors.
Soho posted 08-16-2001 10:49 AM ET (US)     Profile for Soho  Send Email to Soho     

Can you clarify "inflection point" for me. Looking at my chines last night, I wondered if that meant the point where it starts to lift up from the horizontal ? Thanks in advance.


andygere posted 08-29-2001 11:42 PM ET (US)     Profile for andygere  Send Email to andygere     
Having marked the hull and hauled out the boat for painting, it looks a lot different. The side with the kicker motor sits at least an inch lower at the stern than the unweighted side. Also, the scum line tends to go above the natural waterline by almost an inch, with some growth on it. I may end up painting waterlines higher than I wanted to. The "inflection" point is where the chine goes from straight to curved.
Soho posted 08-30-2001 10:49 AM ET (US)     Profile for Soho  Send Email to Soho     
Thanks Andy,

The information is still relevant as my bost is (still ! ) upside down, she gets painted next week. I will raise the water line as per your suggestions, makes some sense.



lhg posted 08-30-2001 09:39 PM ET (US)     Profile for lhg    
Remember it's probable that the waterline on the 16' hull, which I was describing, is different from that on the Montauk 17, which most of you are describing. For the newer 17' hull, I would assume BW has a bottom paint diagram for that also. The 17' hull weighs an additional 250 lbs more than the 16' hull, so would sit lower in the water.
dfmcintyre posted 08-31-2001 09:21 PM ET (US)     Profile for dfmcintyre  Send Email to dfmcintyre     
Having watched the local shop remove the taped waterline from a friends 25 Revenge and redo it, only to find that it's _still_ off by _inches_, I've come to the conclusion that the _only_ way to get an accurate waterline is by stocking the boat with fuel and other items that way it would normally sit, moored at the dock (which may differ considerably from when your cruising with her...) and:

1 - mark the waterline fore and aft with a grease pencil (no need to sketch or trace it along the whole side, unless your a glutton)

2 - rent a laser from the local rentall place. Not a standard laser level, but a rotary laser, the kind that spins and transmits a laser light. You may have seen one in use in a new building where they are popular to let a line for a drop ceiling.

Set it up to hit both grease marks, probably three to four feet aft of the bow, about 10 feet to the side of the boat. That way it will hit the sponson area well.

Depending on preferences, you might go right to the water line, or 1.5" to 2.0" above the greasemark.

Best - Don

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