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Author Topic:   Deadrise Information Needed
Jarhead posted 10-26-2003 09:32 AM ET (US)   Profile for Jarhead   Send Email to Jarhead  

I've searched the Boston Whaler web-site and the '03 catalog but have been unable to find the degree of deadrise on my '03 160 Dauntless.

I know the approximate degree but would like the definitive answer.


Jarhead posted 10-28-2003 07:11 AM ET (US)     Profile for Jarhead  Send Email to Jarhead     
Barry posted 10-28-2003 07:57 AM ET (US)     Profile for Barry  Send Email to Barry     
I found an old ad from Hampton Watercraft & Marine that lists the deadrise for a 2003 160 Dauntless at 16. I've no idea if that is correct. I would suggest emailing Whaler.
jimh posted 10-28-2003 09:23 AM ET (US)     Profile for jimh  Send Email to jimh     
Concern over the number of degrees of deadrise seems to be growing in our collective psyche. I am not sure if it makes a huge difference. In another thread the deadrise of a classic 22-foot hull was examined and measured in several ways, and there was a plus or minus one degree accuracy, from 17-19 degrees. This is on a hull with a very definite constant-deadrise vee form.

Some Boston Whaler boats have hulls with a rounded bottom, like the new 170 MONTAUK or the old SPORT-15, and it seems difficult to determine what the "deadrise" angle is, given that it is not a distinct vee-hull form.

You can always resort to making some measurements and using some trigonometry, or to using a protractor, or hanging an inclinometer against the hull to deduce the deadrise.

But I have to wonder if a boat with an 18-degree deadrise runs better than one with a 17-degree deadrise? I sense that there is more to the overall ride quality than a degree or two of deadrise.

Does the 160 DAUNTLESS have a distinct Vee-hull form?

Moe posted 10-28-2003 10:40 AM ET (US)     Profile for Moe  Send Email to Moe     
Here's an example of what jimh's talking about:

Where are you going to measure deadrise to on the 15 Classic on the left? The upper point inside the sponson? That doesn't tell you about the whole hull. The chine? That would at best give you an average, but wouldn't describe the center of the hull.

The 150 on the right, virtually identical to the 170, is a LITTLE easier, but again, where are you going to measure from? The chine? The inside of the sponson (where the vertical marks are)? The inside of the sponson to the strake? To the center of the hull bottom (there is no discernable keel)?

To calculate a deadrise on these variable pitch (rounded) bottoms, with reverse chines would be about as difficult as doing it on a variable pitch prop. Sure it could be done, but a deadrise figure wouldn't tell you what happens when the stern enters a wave, like looking at the hull shape might.


Tom W Clark posted 10-28-2003 12:49 PM ET (US)     Profile for Tom W Clark  Send Email to Tom W Clark     
Deadrise figures are confusing mostly because we think of deadrise in terms of the angle on the bottom of a V-shaped hull. There was a thread some time ago where we argued about the deadrise of a Montauk.

I argued that you couldn't measure or quantify deadrise on a hull like that because it was not a strict V-hull. Where do you measure the angle? The argument was fed by the fact that Whaler now (or did at the time) have a deadrise figure for the Montauk (maybe it was the Guardian version) that was, if I recall correctly, 16 degrees which makes it seem much more "Deep-V" than I think it is.

The truth is that deadrise can be measured on any hull but the definition of deadrise in the traditional form is the (to quote Chapmans) height between the bottom of a vessel and its widest beam, also expressed as an angle.

This leaves quite a bit of room for the marketing guys to twist the truth, no? I would agree with Jim in that we perhaps obsess about simple figures like deadrise too much instead of assessing the overall performance of a hull.

Jarhead posted 10-28-2003 06:32 PM ET (US)     Profile for Jarhead  Send Email to Jarhead     
It's a simple question.

Whether or not it makes a huge difference or someone might think we are obsessed with simple figures is irrelevant.

I guess I need to explain the reason I asked the question. I read a very interesting article on another site about deadrise and need the information to add to that discussion.

Barry. Thanks for your reply...

Tom W Clark posted 10-29-2003 10:44 AM ET (US)     Profile for Tom W Clark  Send Email to Tom W Clark     

My point was exactly that is is *NOT* a simple question. Or to put it another way, the simple answer to that question is: It depends.

Unless one agrees on exactly how deadrise is measured, simply using some number provided by others to compare two hulls is meaningless.

Gigabite posted 10-29-2003 12:04 PM ET (US)     Profile for Gigabite  Send Email to Gigabite     
According to specs from Boston Whaler the deadrise 16 degrees
Jarhead posted 10-29-2003 03:37 PM ET (US)     Profile for Jarhead  Send Email to Jarhead     
Gigabite, thanks for confirming the 16 degree deadrise figure.

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