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ContinuousWave: Post-Classic Whalers
Weight Gain in 170 Montauk
|Author||Topic: Weight Gain in 170 Montauk|
posted 03-11-2004 10:54 PM ET (US)
Where exactly is all the extra weight hiding in the new 170 v. the lighter classic?
I have heard a lot of speculation about why it may be heavier but I haven't heard anyone specify exactly how this boat grew by so much. Is it thicker glass and resin? It's larger overall size? All of the above?
|Tom W Clark||
posted 03-12-2004 01:47 AM ET (US)
There are two basic reasons why;
1) It's simply a bigger boat, both in length and width but also in total volume in general.
2) The hull is composed of three fiberglass skins instead of just two skins as in the classics.
I do not believe the fiberglass layup schedule is any different.
posted 03-12-2004 06:19 AM ET (US)
This is a darn good question!
I have not had the chance to carefully examine a 170 Montauk, but I would surprised to learn that there was an entire sub-deck beneath the cockpit floor. I know in the stern there is an enclosed and finished area beneath the deck.
Tom (or others)--Is there really a double top shell over the whole boat?
posted 03-12-2004 06:43 AM ET (US)
I don't believe there is a double top shell over the whole boat. In the stern, under the steps, there is a enclosed, unfilled area.
Look at the drawings at whalerparts.com and you will see the boat is completely foam filled. (sorry Jimh if you may not be able to access these drawings).
If you put the classic Montauk beside the 170 Montauk you will see the difference (except for the 3 layers of fiberglass as Tom mentions.) The 170 is much more boat than the classic. Longer, wider, thicker, higher...
|Knot at Work||
posted 03-12-2004 09:31 AM ET (US)
posted 03-12-2004 10:00 AM ET (US)
I thought about the extra beam and extra length when I was trying to figure out the extra weight. With that in mind I came up with the following:
LOA 16' 7"
Post classic 170:
I guess I am puzzled that an additional 3" (.015) in length and 8" (.108) in beam could increase the overall weight by 47%. Looks very disproportionate to me. Just sounds like a lot to me without there being some major structural or material differences.
|Tom W Clark||
posted 03-12-2004 10:21 AM ET (US)
Look at the volume of the hull, not just the length and beam. We can get a good idea of a hull's volume by looking at how much water it will displace when submerged, and we can very simply calculate that by looking at the swamped capacity of a given hull.
The classic Montauk has a swamped capacity of 2000 pounds. The MT170 has a swamped capacity of 3400 pounds. The difference in dry hull weight between the two (using the figures mentioned above) is 450 pounds so there is a 950 pound net difference.
In other words, the MT170 displaces 950 pounds more water than the classic Montauk or almost 16 cubic feet of added volume!
Jim & Erik,
We know there is accessible space under the steps in the rear. Where is the seam between this covering piece and the solid, foam filled hull?
posted 03-12-2004 10:22 AM ET (US)
Don't forget that the sides and transom are thicker. ( I estimate 3/4-inch). They are also quit a bit higher and all in one plane...this will surely increase the weight significantly.
posted 03-12-2004 10:37 AM ET (US)
Your statement that the new 170 Montauk has three fiberglass skins is incorrect. This boat is still simply a hull and innerliner. However you are correct in the fact that the added weight is mainly due to the added size and volume.
posted 03-12-2004 10:45 AM ET (US)
From what I have seen in my 170: the seams are in the corners of the steps themselves. i.e. If you would cut away the steps in the corners you would be looking at the solid foam filled hull at appprox the same level as the deck. Even the rear vertical section in front of the motor, between the steps, is solid-foam-filled.
The bilge area and the cable-canal running from the stern to the console are the only unfilled sections.
The area under the steps may be a bit lower than the deck itself, but I am not sure of this.
|Tom W Clark||
posted 03-12-2004 11:05 AM ET (US)
I stand corrected.
So if you removed the steps, you would be left with the same basic shape in the stern as the classic 16' 7" hull?
posted 03-12-2004 11:07 AM ET (US)
Yes Tom, this is correct.
|Tom W Clark||
posted 03-12-2004 11:12 AM ET (US)
But I do not see any caulked seam. Are these seperate "step" pieces 'glassed in after the hull is molded?
posted 03-12-2004 11:38 AM ET (US)
IMO there are no caulked seams. It looks as if it's all one piece. The corners have a fairly large radius as well. Maybe they are glassed in after the hull is moulded as you stated. I don't know. If so, you surely can't tell.
posted 03-12-2004 11:58 AM ET (US)
I think it is obvious to most that the 170 is a larger boat than the original 17, hence the additional weight.
But what is not so obvious is why it weighs approximately the same as the original 18 Outrage, which is a larger hull, both beam and length. Although the 18 has been shown at 1250# continuously, actually lighter than the 170, I've never believed it and would be more comfortable with a figure more like the same 1400#. But still the size to weight comparisons here are baffling. Anybody with some thoughts on this?
posted 03-12-2004 12:58 PM ET (US)
Tom - regarding your 16 cu.ft. of additional volume - that is correct - BUT, the majority of that volume is foam - which doesn't weigh all that much. Making a few guesses, if the glass "shells" were each 3/8 inch thick and the total average "sandwich" thickness were 3 inches, the foam would consume about 75 percent of that volume. So, in my mind, the displaced volume is informative - but does not explain the extra weight.
I, as virtually everyone, do not know where the added weight comes from - but it has to be glass - or other dense materials. And from past experience, glass is not all that heavy. Frankly, the 450 pounds weight difference surprises me - as that is a LOT of glass. If there were strength or durability defeciences that required beefing up - everyone would have been aware of those problems. There are none - therefore, there was no technical need to "beef up" the hull.
Regardless - the added weight has to come from added glass - either in "beefing up" the hull or the increased length, beam and depth. Definitive information from BW would be most appreciated as there have been and continues to be questions regarding this question.
Also - should anyone have the density of fiberglass, I would appreciate your listing that number. I have looked in a lot of my books - all older - and have not seen the numbers. ---- Jerry/Idaho
posted 03-12-2004 01:45 PM ET (US)
When you look into the enclosed space in the stern of the 170 MONTAUK, are you looking at the hull bottom inner surface?
posted 03-12-2004 02:47 PM ET (US)
I just took off the cover of my boat and had a detailed look inside the rear starboard step. It is NOT completely hollow as I first suggested. For this I apologize ! Just behind the port hole there is an area (approx. 1/2 the size of the step) that goes back to the transom. The depth of the area is a bit lower than the deck. The bottom and left side are neatly gel-coated. Looking inside the hole to the right, you can see red coloured fiberglass mat. This is in the vicinity of the rubber grommet where the gas lines and cables are put through. Here there are sharp threads of fiberglass.
I wonder how some people screwed their kicker-motor bracket onto the transom as there is no way to get to the nuts for the bottom bolts. ( if through bolted).
The cross section drawings available from whalerparts.com are very misleading indeed.
Here are the 3 hulls (18-foot Outrage, 170 Montauk and 16,7 Alert = Montauk) beside each other.
posted 03-12-2004 03:13 PM ET (US)
Erik, that is pretty 'trick' the way the cleats are mounted on the alert...
posted 03-12-2004 03:26 PM ET (US)
Here is a link to some drawings of the 170 Montauk. I made jpg's of the drawings on Whalerparts.com for those who aren't able to open them.
If you look at the cross-section of the starboard-side step it seems as if it's hollow on the inside. The cross-section is correct however.
Cape_rover, here are some more details of the Alert:
posted 03-12-2004 04:33 PM ET (US)
"Definitive information from BW would be most appreciated as there have been and continues to be questions regarding this question"
Jerry Townsend has summed it all up in his response above. We all have theories and they all make sense to some degree but when you get right down to it none of them can account for 450 pounds worth. Lets face it 450 pounds is a lot of weight in such a small boat.
Maybe the guys from Edgewater can respond with the real story so we can put this difficult one to rest.
posted 03-12-2004 08:41 PM ET (US)
How did you mount those rod holders to the gunwales? I didn't think there was any backing in that area? Thanks.
posted 03-12-2004 11:15 PM ET (US)
A small sheet of fiberglass is not really that heavy but try to lift a bunch of it. It does get heavy. Not only does the fiberglass add weight but what you use to saturate it with (resin) is also quite heavy.
posted 03-13-2004 03:41 AM ET (US)
I sent you an e-mail explaining the procedure for mounting these rodholders. This way we won't get off topic.
posted 03-13-2004 07:30 AM ET (US)
Here is an interesting link called the fundimentals of fibreglass.
posted 03-13-2004 10:16 AM ET (US)
What is the gunwale height on both montauks?
I don't see where swamped capacity and hull
weight have anthing to do with additional
volume in both boats.IF that theory was correct
it should work on other models also.Try it on
the 23 and 240.
One cubic foot of cement displaces the same amount
|Tom W Clark||
posted 03-13-2004 10:16 AM ET (US)
I really don't see what the mystery is. While it is obvious the hull has a much greater volume and one could argue that foam doesn't weigh much, it still weighs something.
But the point that I think is being overlooked is that the extra volume of foam has to be contained in something, and that something is fiberglass. It not a difficult concept to understand.
This boat is bigger. It's longer. It's wider. It's deeper. When we talk about something being larger in one dimension, you have to remember that the size of a three dimensional object increases by the cube of that dimension.
The more compelling argument that something may be odd here is Larry's comparison of the MT170 to the classic Outrage 18 which had a published dry hull weight of only 1250 pounds, actually less than the MT170!
But we have strong evidence that Whaler simply understated the weight of that hull. In fact, certified scales seem to suggest the Outrage 18 really weighs closer to 1500 pounds.
Now looking at the swamped capacity of the Outrage 18 we see it is 3000 pounds, still less than the MT170. I would speculate that the Outrage 18 has more fiberglass but less foam than the MT170.
In all this arguing about the weight of the MT170 and how is is an unfair comparison to the Classic Montauk the thing I see as remarkable (and not commented on much) is the fact that now that a few of these boats are in the hands real people, the MT170 seems to perform almost as sprightly as the Classic Montauk when powered with comparable motors.
If the MT170 weighs almost half again as much, shouldn't it only go two thirds as fast? It would seem to be a very well designed hull.
Would you now conclude that the steps are molded with the inner hull liner and that the space for passing the rigging from the tunnel to the motor well is cut out after the hull is molded?
posted 03-13-2004 11:44 AM ET (US)
Erik - thanks a million for the link regarding fiberglass. Appreciate the information and everyone should read and save that information. I wish, however, that the authors had used typical (or a range) numbers instead of ranking as P(oor), E(cellent) and F(air) - but then there are many uncontrolled variables that can really change those parameters.
I have used fiberglas for many, many applications (rocket engines, canoes, horse trailers, et.al.) many years ago and have published data around here someplace - but can't put my hands on it - and may even have tossed it.
Tom - one has to be carefull regarding speed comparisons and extrapolations - as there are several parameters of importance - weight, yes - BUT hull form design and wetted area, et.al. ------- Jerry/Idaho
posted 03-13-2004 12:50 PM ET (US)
Erik, to answer your question, I could not through bolt the lower 2 screws to the transom. It is difficult but I believe can be done with the right measurement?
That is a nice setup on the Alert. Very creative.
Is the port step filled with foam?
I seems to me that the added volume of fiberglass, both mat and resin makes for the difference between the weight of the two boats.
posted 03-13-2004 01:10 PM ET (US)
Here's a visual comparison of the 900 lb 150 Sport, 950 lb 17 Montauk, 1400 lb 170 Montauk, and 1250 or 1500 lb 18 Outrage:
The 170 is about 2.5% (5") longer than the 17. Its 82" beam is about 11% (8") wider than the 17's 74" at its widest point, but as you can see from the drawings, the 17 gunwales curve in at the bow and stern, where the nearly straight-sided 170 is wider yet. The width of the cockpit sole on the 170 appears to be about 66" compared to about 55" on the 17 (20% wider).
While the drawings are only 2-D, they give a clue as to the depth. Look at how far in and back the sponsons protrude into the cockpit sole in the 17--all the way back to the aft end of the console. In Eric's picture here, the 17 Alert is closest to the camera and should have an advantage in size perspective, but it still looks smaller than the 170.
Also note the differences in the sponsons at about amidships. The 17 narrows from the tops of the gunwales down and then angles inward sharply to the lowest part of the sponsons, which are like a V. The 170 seems to maintain its beam with a more vertical gunwale, not only down to the sponson, where the gunwale steps in slightly, but beyond that down to the lowest part of the sponsons, which are like so \| comparatively. This accounts for even more 3-D volume in the 170.
The amount of foam can be estimated from the total bouyancy:
Total Bouyancy (hull weight + swamped capacity)
The 18's slightly larger overall size (more fiberglas) and slightly lower total bouyancy (less foam) appears to back up Tom's assertion about the 18 vs 170.
As said above, 170 is a larger boat than the 17, which is about the same overall size as the 4" beamier (at the 17's widest point) 150 Sport.
posted 03-13-2004 02:31 PM ET (US)
At this point in time I am unable to make a conclusion as I still am puzzled about a few things. I have an idea about how the steps have been constructed and I am working on a drawing that I will post as soon as it is finished. I will leave the conclusions up to people with more experience like you and others around here. I just spent 30 minutes looking inside the porthole trying to figure out why the side of the splashwell is bare fibreglass (and thin) on the inside. The front(inside part) of the splashwell is solid and neatly gelcoated.(and foam filled). Looking on top of the splashwell you see no seam at all. Everything is as smooth as a baby's bottom and has a nice large radius...Anyway, I think some drawings and more pictures will say more than a thousand words. I'll try to post them some time tomorrow.
Jerry, there is indeed alot of information on that website. In the menu "Learning Center" you will find all sorts of interesting stuff like physical properties, charts, conversion tables...
Sam, I don't know at this point if the port step is filled with foam. The step on the starboard side seems to be very thick (approx. 1-inch)and also seems to be resting on a vertical section moulded in with the hull.(here you can see a seam) The bottom of the step (inside) is also bare fibreglass. I don't know if the port side would be symmetrical to the starboard side in this case.
Dirk Thyssen's 1988 18-foot Outrage weighs 1540lbs not including traler, motor, fuel, batteries and extra's. His rig has been weighed several times at the 2-yearly automotive inspection of his rig with trailer. (mandatory over here for insurance purposes).
posted 03-15-2004 03:18 PM ET (US)
I took some pictures and added some notes to give you guys an idea of how the steps and the splash-well are assembled.
Maybe Tom, Jimh, Moe and others can figure out how the steps and splash-well sides have been integrated.
On the inside you see many seams and bondings. You will also notice the red fibreglass on the step bottom, splash-well side, step front. The transom, floor (under deck) and splash-well front vertical column are all gelcoated and seem to be part of the hull. When I put my hand in the canal running to the consol, I can feel fibreglass as far as I can reach on the bottom of the deck. The bottom of the canal however is smooth and gelcoated.
I hope this gives you guys a better idea of how it all fits together.
Here's the link to the pictures.
posted 03-15-2004 03:41 PM ET (US)
The only thing that I can add to Erik's statement is that the rigging tube is a heavy duty PVC drain tube (per B/W).
posted 03-15-2004 03:53 PM ET (US)
I've been thinking about this for awhile, and my guess is that while the cockpit shell (and the outside of the steps are part of that) is still in its mold, another piece of fiberglas is epoxied to the underside of the cockpit shell. This other piece probably looks like three sides of a square under the step and it's smooth side is to the inside of the step, so its rough side will bond to foam between it and the rough side of the hull shell. Those three sides are the back, left, and bottom as you look into the access hole.
That's what I'd thought until I saw the bottom picture on that page, and it looks like that 3 sided piece actually has a piece of a fourth side that extends in front of the splash well and provides structural support between the inner and outer front wall of the splashwell.
Whether this piece goes all the way over to the port side step and does the same thing is a mystery, but it sounds like it extends forward on the underside of the cockpit shell, up to console, passing the gas hose outlet on the way.
I'm pretty sure this is all bonded to the underside of the cockpit shell before it is mated with the hull shell and foam is injected between them.
That's my take on it.
posted 03-16-2004 01:59 AM ET (US)
Whatever the construction methods it sure looks like they should have gelcoated the fiberglass in that corner.
Moe & Erik--great visual aids. It's a good shot of the hull sizes and forms. What stuck out to me wasn"t the size diffence between the 170 and the 17'Alert, but what a Monster the 18 Outrage is.
It is also interesting to see the deck space comparison where the width of the 170 and the 18 Outrage, inside gunnel to inside gunnel, look comparable.
The 170 may have a visual advantage over the 17' Alert, because it isn't sitting on its factory trailer, the boat is much too high above the fenders. Gunnel heights are similar when on the water.
posted 03-16-2004 08:11 AM ET (US)
Erik--Thank you for taking those interesting pictures, adding the callouts to them, and posting them on your website. I still don't think I comprehend exactly what is going on in the construction!
Next time I come across a 170 MONTAUK in person, I will have to hang my head down there and take a look for myself.
The construction looks rather crafty. It certainly helps the aesthetics of the boat, as it hides most all of the wiring, cables, and hoses. That is a big advantage. If it comes with a small weight gain it is not a large price to pay.
|Tom W Clark||
posted 03-16-2004 10:30 AM ET (US)
Thanks for taking and posting those photos. They are extremely illuminating. From them it certainly appears there is a separate piece that is 'glassed in after the hull comes out of the mold.
The last photo is most telling. There we can see how this separate piece wraps around the end of the forward portion of the splashwell.
I have to presume they fair the gel coat transitions after the hull is molded and from the looks of it they do a very good job of it.
|Tom W Clark||
posted 03-16-2004 11:56 AM ET (US)
I am going to retract my comments above. I think Moe had it correct. The separate piece is 'glassed onto the back side of the starboard step then the two parts of the hull must be assembled and filled with foam.
This separate piece would create what we call in concrete forming, a "block out" which leaves a void in the material being cast, in this case, foam.
posted 03-17-2004 08:31 AM ET (US)
Another place where some weight could be gained is in the area between the deck and the keel. The hull form on the 170 is a deeper vee than the old Montauk 17, so there is more interior volume.
Compare the shape of the hull when sawn in half. For a photograph of a traditional Whaler hull, see:
For a photograph of the newer hull form cut in half, see:
Now in those images neither of the boats are a 17 or a 170, but I think the general trend in the hull shape applies.
posted 03-18-2004 08:15 AM ET (US)
This is absolutely correct jimh.
I don't find it surprising at all that the 170 Montauk weighs alot more than the classic Montauk. For those who have seen both boats side by side in the water (or out) for real, it's quit obvious. The 170 is just bigger. More bulk.
What surprises me more is the difference in weight between the 170 Montauk and 18-foot Outrage. The rated 1225lbs for the Outrage is ridiculous. It is in fact, as Tom and also Larry (LHG) suggested (in an earlier thread) more. As I stated in the above post: Dirk's weighs 1540lbs. This is more in line with what you would expect for this boat.
The comparison drawings posted by Moe are exactly correct.
IMO the 170 Montauk leans much more to the classic 18-foot Outrage than it does to the Classic 17-foot Montauk. This in every way: weight, dimensions, ride...
Matt, don't let the picture of the 3 boats "side by side" mislead you. Look at how high the Outrage is sitting on the trailer. (The Alert also for that matter) Higher than the 170 Montauk. None of these trailers are trailers you will find in the USA. The roads here in Europe are not as wide as you will see in North America. Our trailers are in general not as wide as i.e. an EZ-loader. Giving us a bit more space and clearance for manoeuvring and passing through toll booths for bridges, tunnels and some highways.
Thanks Moe, Jimh and Tom for your thoughts on how the steps are integrated in the 170 Montauk. Wouldn't it be great to pay a visit to the factory to see how they put these hulls together? I guess not many people are allowed to see how this is done.
posted 03-27-2004 05:46 PM ET (US)
Just came back from the Palm Beach Boat Show. Talked to a BW factory guy who gave me the factory answer to this question.
"It is just a bigger boat"
posted 03-27-2004 06:14 PM ET (US)
But it's not bigger, nor with more offshore capability, than the 18 Outrage. It has no built-in 63 gallon tank, no heavy plywood tank cover, a smaller console. The mystery continues.
posted 03-27-2004 06:20 PM ET (US)
PS: What about the 90 vs 150 HP discrepancy too? Why can the 18 Outrage so much more?
posted 03-27-2004 10:32 PM ET (US)
Larry, I don't see it as very mysterious if the 18 Outrage weighs in between 1500 and 1600 lbs on scales in the real world. It's a bit larger than a 170 and weighs a bit more.
Taking 10% off 27 gallons, and then using the 1/3 rule, at 5mpg (four-stroke), the 170 is good for 40 miles out and 40 miles back with 40 mile reserve. In trolling terms, that's 20 miles out, over 10 hours of trolling at 3 mph, 20 miles back, with a more than a 30 mile reserve. It may not have the same range for long distance cruising as the 18 Outrage, but that's not the 170's intended use.
Using the CFR Maximum HP forumula 2(LXW)-90,
The 170 gives 2(17X6.83)-90=142HP
The 19G gives 2(18.5X7.17)-90=175HP
Were the 170 rated at the same 85.6% of CFR Maximum as the 19G, it would be rated at 122HP. That apparently does not suit today's Whaler safety and family images. If the 19 Guardian were again sold today as the 18 Outrage, and rated at the same "safe and family-friendly" 63.2% of CFR Maximum, it would only be rated at 110HP! That's what the math says.
Looking at the 190 Nantucket, the CFR formula gives 2(18.83X8)-90=211HP. It's 150HP rating is 71% of 211HP. If the new 18 Outrage was allowed the 190's higher percentage of the 18 Outrage 175HP CFR Maximum, it could only be rated as high as 124HP.
Times have changed, and that has to be factored in.
posted 03-27-2004 10:34 PM ET (US)
In trolling terms, that's 20 miles out, over 10 hours of trolling at 3 mph, 20 miles back, with a more than a 30 mile reserve.
That should've been a 50 mile reserve, given the total 24gallonsX5mpg=120 miles.
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