Hull ride differences between manufacturers

General boating discussion
hatcher
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Hull ride differences between manufacturers

#1

Post by hatcher »

Hi all - not trying to start a brand war but I can't find much on scale of ride difference between manufacturers in the 22' to 28' size trailerable OB bay/ocean use type class aluminum boats where 14- 18 degree deadrise is common. I have a 22' Alumaweld Intruder with a 14 degree deadrise in the back and Yami 225. It's a light boat (less than 4k lbs fully loaded) with a minimal deadrise. I originally purchased it because it was my first boat and you can run it with a jet or prop and I wasn't sure what I would do more of. I've now spent many, many hours pounding away in the salt in the Puget Sound, Straights, Ocean and San Juan Islands. We love salt water boating but sometimes take it to lakes for tubing etc.. It has worked for us and we love the boat and the utility of the size in that we can launch on small lakes and pull kids on tubes or go butt fishing out of Neah Bay. I've often thought of getting a bigger boat or boat that is thought to be particularly good in the chop. I've definitely noticed big NON ALLOY boats with lots of HP and weight do better but they are burning loads of fuel and look like a real pain to trailer and launch so I'm not interested in that. I haven't noticed other Aluminum boats going substantially faster or smoother than us. Sure a little for bigger boats but not much. So just how much difference is there really in this world of alloy boats that we love? In threads brand preferences are thrown out and some brands have taken on a bit of mythical lore when it comes to ride quality (Edge Marine guys swear by them) but as most of our boats (at least ones in my size) are very similar, aren't these boats essentially very similar in how they ride on the water with modest improvements here and there? Some alloy boats are now incorporating more significant deadrise with wider bottoms and large reverse chines. Is that really a huge deal or minimally better or better at all? Are there negatives like less stability and sluggishness?

This has to be a tough one to measure since most folks are similar to me in that you go as fast as the water lets you which means you are taking it up to the point of pounding all the time when there is chop or swell?  :thumbsup:
 
I'd be really interested in thoughts from folks who have owned multiple trailered aluminum boats and have experienced the differences first hand as I'm trying to figure out if it is worth it to get a different boat or stick with what has worked well for us? I tend to buy and hold for a long time unless there is a great reason to get something different. I'd hate to years from now get a different boat and be like man I could have saved myself a lot of serious pounding....  :banghead: 
 
 
JonH
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Re: Hull ride differences between manufacturers

#2

Post by JonH »

A few general points -

All things being equal, a heavier boat will ride better than a lighter one of same length.
There is no substitute for weight but as you noted more HP & fuel consumption also.

More deadrise, particularly in the forward part of the hull will generally give a better ride.

A variable deadrise hull - of which there are few in the alloy hull world - will generally ride better
than a constant deadrise hull.

The further aft your helm & seating areas are the better your ride quality will be - nothing beats sitting on the transom!

Also, proper trimming of the hull via engine trim and/or trim tabs makes a big difference.
 
hatcher
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Re: Hull ride differences between manufacturers

#3

Post by hatcher »

Great points. Makes me think of how bigger pilot house boats with v-berths are going to have the driver further back in the boat which would mitigate the pounding a little vs. my Alumaweld where I'm sitting right up front. Also, makes me think landing craft and center consoles have a big edge on driving comfort.

However, weight, trim and sitting distance from the pound zone aside - is there a best recipe hull for bay / ocean, what are the components of the best recipe (variable deadrise, deadrise degree through bow/midship/stern, strakes, reverse chines etc...) what manufacturers are offering that best hull recipe and how much better is it than my setup (which I would argue is the typical hull for 22-24' boats out there) assuming similar weight and power?
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Re: Hull ride differences between manufacturers

#4

Post by Craigb »

A boat with higher deadrise forward will tend to split waves, rather than try to ride over them. Splitting them is better for overall ride, riding over them is preferred for river/shallow water boats. A narrower beam will also produce a softer ride, as it has less wave to split. The deadrise aft is what most manufacturers report, but this is only really important is the boat becomes airborne or is cornering. A very narrow hull with a splitting bow can produce a very comfortable ride, even if it had a flat hull aft, but going slower has to be ok. Trade offs...
kmorin
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Re: Hull ride differences between manufacturers

#5

Post by kmorin »

Hatcher, JonH,

"RIDE" is a big topic to try to converse about online, being that it's in text not eye-to-eye and on the water boat testing together in a controlled circumstance.  So someone who's spent a lifetime in nearly flat bottom work skiffs will think even a slightly warped bottom 14 degree deadrise at the transom is a 'great' ride.  Conversely, someone who's 14 deg (stern) warped bottom skiff is traveling so fast the waterline is moved 1/2 the DWL aft.... into a relatively flat bottom and is pounding due to the light displacement (momentum) where the 'sharper' bow out of the entry into a chop will think this is a rough ride.  Bit of relativity to these experiences, which you've already noted.

I'll go around some of the various 'points' with you to see if it will help you explore your answer? (If there is an answer?)

I think it's important to recall that as a skiff powers up the running waterline's leading edge; 'moves' aft. Even a jon boat, flat as it is, will 'run up' on the surface and the almost straight transverse line of the forward edge of the running waterline will move aft so any chop will produce a pounding/slapping/bumpy ride.

I think bow pitch/trim by the bow/hull angle to the running waterline is very important to monohedron and warped bottom hulls.  Keeping the sharpest angle of entry into the water/swell/chop will allow the hull's least flat area to form the entry impact area.

As JonH mentions, a deeper V or 'more deadrise' angle will enter the water more gradually (measured in parts of a second) so there's less sudden impact for the same LOA, BOA, & displacement when the bottom is 'sharper'.  BUTTTTT... 

At the same time, when a skiff has a very deep V (greater than 20deg) it will likely roll so bad when trolling or at anchor that you'd likely prefer a good-ole pounding to the snap roll of a light displacement skiff with a very deep V when its not running.

Next is to correlate mass with 'ride'.  A 60's era Volkswagen bug could be driven to 60-70 mph over a 'between the cornfields road' and the ride might jar loose your teeth or hurt your back. However, the same ride in a 1962 Cadillac Coupe Deville would feel like you were floating on a huge pillow that was remotely shaking underneath your seat.  Mass of one is 4800-5000 lb and the other less than 1800 lb.s so ride is extremely influenced by the momentum of the vehicle where mass is a big factor- speed being constant between the comparative hulls.

However, every inch of every mile you cruise with 2.5 to 3 times more all up displacement will cost you that much more fuel- forever.

Most of the skiffs in the class you're describing are built with similar scantlings for the most part there's little difference in displacement for the various designs in different LOA categories.  Where the bottom panels of 20-26'ers (maybe 28') are going to be from 5/32 (0.160") to 1/4" (0.25") plates, with custom built skiffs perhaps offering 1/8" to 5/16"(?), and topsides just one 1/16" thinner overall; the final hull wt is usually coupled closely wt model (ie. cabin or open ) inside this LOA range.

Because the hulls are a limited range of displacement (often a small fraction of plastic boats of comparable LOA) their designers have limited themselves to a range of deadrise and usually use a warped instead of monohedron hull form.  The correlation between LOA and deadrise is the roll limits that a deeper V (>20 deg) would bring, as mentioned above.

One last point to consider about ride is LOA and your typical trips in local waters.  A longer hull will perform most smoothly in shorter period seas compared to a shorter LOA.  The smoother 'ride' in the longer skiff is from less pitch by the bow keeping the forward 1/3 in the water to 'part the seas' with a sharper angle of entry.  At some point in any seaway, the period of seas in the near coastal areas can become short (chop) so the shorter hull might be pitched up and down more- where a longer skiff would ride with less action up and down by the bow.

If you were planing in these conditions the longer LOA would usually give a smoother ride as it could be controlled (trim by the bow) to keep more of the bow forefoot into the wave face. So one change you might consider is to increase the LOA, but if you consider ALL 22'ers there is going to be very subtle differences between the hulls from different builders or manufactures.

And testing them would require an absolute fortune! in order test, you'd need to get all of them in one place with accelerometers installed in all of them and all running in tandem in the same sea, with the same displacement, power and load!!!

In the meantime, I hope this long winded review helps you to join the path we've all beat around this particular hull design 'bush' for so long. Might try 'utube' topic "Jahrig Aluminum Boat Build" # 52 and see what I tried to create in a 34'er as far as keeping the bow down, having sharp entry, and to reduce roll when the hull is stopped or fishing. 

Cheers,
Kevin Morin
Kenai, AK



 
 
kmorin
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Re: Hull ride differences between manufacturers

#6

Post by kmorin »

hatcher,
you've mentioned reverse chines and I wanted to address them in light of my previous remarks.

If you leave the hull's chine to chine beam the same between two boats of the same LOA and (relative) displacement you could sharpen the deadrise/V bottom angle by putting reverse chine flats inside both chines immediately inside the topsides to bottom hull intersection.

Many designers do this to help increase the hulls' entry angle and potentially soften the 'ride' and use this displacement transition as a means to throw water off horizontally (or away) from the topsides as the hull is immersed into a wave face. So reverse chines will not only A) help the hull afford to have deeper V/higher deadrise, B) it will act as a spray rail and C) this chine flat could be carried aft to the transom to help provide a 'sponson' to reduce roll when compared to the same V carried to the chine in another hull.

Another chine design element that is worth noting in discussing bow entry to a wave is the height of the chine's intersection with the bow stem- the line of the topsides meeting at the bow (in Profile View)  IF the chine is carried higher toward the sheer line at the bow stem intersection; the V depth of the bottom is increased without lowering the keel line, instead, by  raising the chines toward the bow.

Another item, not often discussed, but something I've used in my designs for 40 some years, is to rake the transom angle aft to 20-24 deg instead of the more common 12 deg.  Most outboards in the 100hp+ range have power trim/tilt.  The power trim will tuck the leg, vectoring the bow down, but only to the amount allowed by the transom angle.  There is plenty of trim out- to get the bow up, and soon the tilt takes over to lift the leg for launching and landing.  But.... I prefer to allow a great deal more 'tuck' so the bow can be 'held down' to a nearly flat or 2 deg.s pitch up- since that allows any V bottom hull the ability to trim bow down, and thereby finding a sweet spot for the speed, seas and hull so that a compromise for more conditions are met by raking the transom aft another 12 deg.s over the recommended 12deg.

Helm stations further aft also help ride, as you've mentioned.  Notice the extreme example of ocean racers- three guys literally with their seat backs to the inside of the transom. One helmsman, one throttle man, one navigator trim man... at the speeds they go water is hard as rock, and the impact requires pneumatic seats.

That brings up another idea. What about exploring fully impact articulated seats? Might make the whole question of moving to another hull academic?

Cheers,
Kevin Morin
Kenai, AK

 
 
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Re: Hull ride differences between manufacturers

#7

Post by hatcher »

Nice - thanks for jumping in on the discussion guys. Kevin that Jahrig Aluminum Boat Build looks pretty awesome. So I'm going to try to boil this down a bit but again focusing on the hull vs. other variables like drivers position or suspension seat which I do have not but I get the point that not all suspension seats are created equal.

My key takeaways are:

Biggest factor seems to be having a deep v at the impact point so that you slice through the waves vs. bounce off the top.

Deeper v = better slice through the water but sacrifices stability while fishing and perhaps speed as it could be a less efficient plane with more wetted surface vs. flat bottom with higher fuel costs.

Longer boat = the boat in short chop being able to keep it's nose down or deeper part of a variable V in the water as it is able to ride across more and resist as much lifting in the front.

Higher mass = better ability to press the v into the water, but you pay for this in extra fuel burn

Large reverse chines = ability to have a more aggressive degree of deadrise while have some stability benefit. I don't know if I have seen a 22' plus NON ALLOY boat without large reverse chines. Hmm...

Ability to aggressively trim the nose down = ability to press the v into the water, but again you pay for this in extra fuel burn but if this can be done with trim tabs or more aggressive rake of engine transom than you can trim back out of this inefficiency so that when not needed you can run faster and with less fuel burn.

So for me the most appealing features are ones that help me avoid simply adding more mass which forces me to lose some of what I love about alloy boats (easy to trailer, light to trailer, easy on the wallet for fuel burn, drives like a drag car vs. a lumbering 50's Cadillac). So a hypothetical great hull formula is one that is long, has a relatively deeper V (18 vs. my current 14), large reverse chines to help maintain stability and trim tabs (finding an aggressive rake to the engine transom would be difficult).
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Re: Hull ride differences between manufacturers

#8

Post by kmorin »

hatcher,
I think you've stated a pretty good summary of the welded boat shape attributes that contribute to a good ride.  There remains a discussion of structural framing ideas but the shape that meets the water is what mainly determines ride.

Only issue I see is the idea of trim tabs and transom rake.  Being metal boats- you can modify the stern anyway you'd like- so a 24 deg. stern can be put on anytime- or even just a plate or two to lean the engine mount bolt plate aft. Not hard to get done by any competent aluminum welding shop.

Next is tabs, flat/flap tabs are some pretty heft drag to do what we're discussing in regards trimming the bow down for a long run- Bennett (brand & type) trim tabs work, but are lots of drag.  The newer vertical bar tabs are quite a bit more efficient and do as well or better job.  Imtra's ZipWake vertical bar type trim system seems less drag and more efficient?

But if possible to vector the thrust of the leg/outboard wheel to lift or lower the bow is less drag yet; so less fuel overall to keep the bow down as much as possible in the conditions and load you're running.

Cheers,
Kevin Morin
Kenai, AK

 
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Re: Hull ride differences between manufacturers

#9

Post by hatcher »

Totally makes sense on tabs and drag vs. redirected thrust and no drag change. Great point. I was scouting around for more on this topic and came across this hull design overview with Grady White which is really a reflection of Ray Hunt's design so I thought it was a good summary as Ray Hunt seems to have had a pretty big influence on modern NON ALLOY hulls. https://www.youtube.com/watch?v=0KW8e2f-3ZQ

Thought it was pretty good. Adds a few new elements to discussion above but really reinforces much of the discussion so far. I also found this article that has more detail on the tuning of spray rails and chine widths / angles. https://boattest.com/article/spray-rails-and-chines

Would love to hear from someone who has owned both a boat like mine (22' Alumaweld Intruder) or at least spent a substantial amount of time on one driving and not just as a passenger and a boat like the Edge Marine (has 20 degree deadrise and reverse chines) to weigh in on just how much improvement these design elements make.

I think Edge Marine is an excellent comparison to my Alumaweld for this discussion as both have canvas tops so more similar mass profile for non hull elements vs. pilothouse type boats which bring greater mass from the pilothouse structure into the equation. I know other manufacturers and custom builders also have incorporated larger deadrise and reverse chines and have canvas tops so would also be good comps: Duckworth Pacific Navigator, Boulton Sentinel Pro/XL are a couple I found.

@Kevin it would be soo cool to put accelerometers in and do proper testing across different boats! Hmmm is there an app for that? Don't we have built in accelerometers in our phones now, might actually be something possible there... I'm perfectly willing to go out of Everett WA and slam across to Langley WA with owners of good comparison boats for lunch and compare results. Especially if I can drive the nicer riding boat back for comparison purposes! ;-)
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Re: Hull ride differences between manufacturers

#10

Post by JonH »

Hi hatcher

The Grady-White / Hunt video is excellent - good find!

Hunt also does alloy hulls, primarily pilot boats but they do some smaller alloy hulls, typically one-off
customs such as my 28'. Their alloy hulls are also variable deadrise.

Attached photos of a 70' Hunt pilot boat and my 28', in service for 5 seasons now.
You can see the family resemblance between them as well as the Gradys.

Jon

 
 
 
 
 
 
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Re: Hull ride differences between manufacturers

#11

Post by JonH »

My 28'.
 
 
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Re: Hull ride differences between manufacturers

#12

Post by welder »

Alloy boats will ride rougher the there plastic counter parts due to weight of the boat, roughly 2/3 the weight, so that gives us fuel milage and carrying capacity, but we sacrifice ride some.
The best thing I've seen/done in the Pacific 23 is add trim tabs, learn how to attack the swells/waves at a good angle and if it's a bit sporty out there don't get in a hurry and try to make time with your throttle.
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Re: Hull ride differences between manufacturers

#13

Post by chille51 »

kmorin wrote: Fri Nov 04, 2022 1:56 pm hatcher,
I think you've stated a pretty good summary of the welded boat shape attributes that contribute to a good ride.  There remains a discussion of structural framing ideas but the shape that meets the water is what mainly determines ride.


 

 
Yes, have been eagerly following the discussion on this thread and trying my best to align it with the ideas on structural framing shared in the thread I started a couple weeks ago in the "shop talk" section of this site.  Also have re-read an older thread I believe you started Kevin about foam vs no foam in the hull.  Seems to me the shape, the structure, the weight, what fills the gaps, they all go hand in hand, especially if you expand the scope of the discussion beyond purely ride comfort to include safety and durability.  Great info all around and excellent summary of the key points thus far hatcher.
 
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Re: Hull ride differences between manufacturers

#14

Post by kmorin »

hatcher,
looking at the Grady video there were several term revisions that are examples of how we (all) mis-use our terms sometimes.  The intersection of the topsides panel to the bottom panels' outer most 'edge' is a The Chine.  This is a single line of intersection- not a flat area - but a single line of intersection. A chine flat or double chine is what was being discussed on the video; Grady's spokesman is welcome to mis-use the historic terms but in this case he's going against years of common use.  More common is to describe an inner and outer chine- and he didn't mention that is very common, at least in welded hulls, for this 'chine flat' to be angled upward or downward a few degrees depending on the fore aft location in the hull.

I do agree with most of what he said in regard the other hull shape behaviors except he's missed on very significant point regarding the rounded keel instead of a sharper V.  The seaplane experiments referred to were in WWII and all the planes involved traveled at speeds very much higher than anything except the open ocean offshore racers of today- even then not many boats traveling at plane speeds.  The Reynold's No. of water ('hardness of water') is mainly influenced by how fast you impact or enter the water.  At airplane speeds, the Reynold's # is concrete level high.  That is when the entry is aided by a radius but that's not the case for <50 mph in general terms.  So I don't regard that idea of rounding the keel as holding much water- at even fast recreational boat speeds.

The spray rails or 'lift strakes' between the chine and keel as they are sometimes called, have all sorts of properties and he enumerates them pretty clearly. One benefit they serve in welded boats that can be very cost savings but not applicable to plastic boats' builds- is the longs being outside the hull instead of inside where they'd have to intersect the transverse framing and bulkheads.  By locating the bottom framing longs outside the hull's bottom plates; they don't intersect w any interior framing which saves notching, fiddle welding, sealing bulkheads w/ notch patches, welding planning and compartment testing of much greater complexity than if the x-verse framing is inside and the longs are outside the hull panels.

I'd also note the actual true "Flare" of this hull (shown). The shape of the forward 1/3 of this cast-in-a-mold hull has a curve in the Body Section View (hull slices at 90 degrees to Keel & Waterline) as well as the Plan View (top down viewed slices parallel to the Waterplanes) - the Grady hulls' topsides are a compound curve allowing a very much more effective vectoring/guiding/throwing of water away from the hull than the "Flam" we see in 90% of the plate boat where any given Section of slice of the hull has a nearly straight line from chine to sheer.

Plate hulls rarely have real flare- compound forward topsides sections. The reason is the level of effort needed to form 'planks' or panels that would have that shape.  This work requires actually compound bending/rolling of the topsides in sections then rejoining them to conform to a framed shape and pulling the entire surface fair/smooth to that prefabbed frame. 

This also involved much more welding.  Typically a five-panel hull has little or no butt welds in the main hull as sheet/plate is available in 20 -30' lengths. This means the entire topsides of 28' hulls could be one sheet, the same with the bottom panels- this could eliminate any transverse welding of the five panel hull 'skin'/plating.  Not true of the planked method of building where compound shapes are formed, trimmed to fit into a framing area then butt welded to one another to form the 'fare' instead of single sheet 'flam' shapes from developed surface designs.

In general, it's simpler work to simply design the topsides forward as a part of cone, then pull it together at the bow stem and call it a day.  This tends to make most plate boats' bow 'spoon' more full and less gradual and so it influences the 'ride' or movement of these boats resulting in a much greater pitch up by the bow- compared to the Grady hull's shown. That is; when the bow on waterline is raised farther and farther toward the sheer- the spoon bow compared to the flared bow will lift the boat much more vertically compared to the narrower flared bow shaped  boat.  The reason is; when viewed from Plan View sections (showing slices parallel to the waterplanes) each inch of immersion grows more rapidly if the lines are bowed out more (cutting through a cone) than if you look at these same lines in a flared hull (ie. Grady White) the 'volute' (cuts) form has much less increase per inch of immersion  (displacement) of the hull as the waterline raises upward.

This results in less pitch up of the bow for a given waterline raise as the hull enters a wave face.

Just refining some of the video contents between welded metal and cast shaped plastic boats for the discussion in this topic.

Cheers,
Kevin Morin
Kenai, AK
 
 
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Re: Hull ride differences between manufacturers

#15

Post by gandrfab »

"Next is tabs, flat/flap tabs are some pretty heft drag to do what we're discussing in regards trimming the bow down for a long run- Bennett (brand & type) trim tabs work, but are lots of drag. The newer vertical bar tabs are quite a bit more efficient and do as well or better job. "

I'm having trouble imaging how a flat dam is going to be more efficient than a smother directional flap.

My questioning post from another boating/fishing forum.

I'd like to see the results being sold (depicted in the picture, explained in the video) in a test tank with die.
And a Distance travel per gallon of fuel burned comparison. 
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0.png
0.png (82.85 KiB) Viewed 5395 times
 https://www.youtube.com/watch?v=QF2BvAPsivo

https://www.marlinmag.com/story/sponsor ... k=16221044

I'd like the finesse of a good old fashion tabs. Unless those dams are only use to get up on plane they are flat faced drag underway. 
 
 
 
 
 
 
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