How to reduce the bouncing/pounding of an aluminum boat

[beemer]

Most of the light boats , aluminum included seem to place the main fuel tank incorrectly to gain more height in the cabin. IMHO fuel tanks in high powered light boats should be midships and forward. If you look at all the large inflatables running around with 12 fat americans seated forward the main tank is low and forward and BIG.

 

[brutus]

Some excellent feedbacks. As mentioned, no issue in calm seas but pounding happens even in smaller chops. I mostly fish in calmer water anyways but time to time, we all can find ourselves in some bigger waves and choppy waters. Thank you all!

Slow down a bit, that will help lol, hug the water don’t jump over it

 

[zurk]

Good luck finding a Rafnar OK hull in aluminum...to my knowledge they have not released one yet and I don't know if they even have a prototype in aluminum running.

“Currently all of Rafnar’s boats are made from fiberglass, however, we do have many requests for aluminum boat builds so we have opened discussions with an aluminum boat builder. Though the curvature of the hull is quite different from a deep v or shallow v hull design, we know that it is indeed possible to build our boats out of aluminum. Due to the numerous requests, we are investigating the potential of having aluminum Rafnar boats sometime in the next two years.”

Inventions Shaping Our Oceans: Rafnar Hull

By Ariadne Dimoulas – This article series will look into inventions shaping today’s seascape. How has our mariner history resulted in today’s groundbreaking inventions? Which inventions direct our future? What...

gcaptain.com

 

[cracked_ribs]

“Currently all of Rafnar’s boats are made from fiberglass, however, we do have many requests for aluminum boat builds so we have opened discussions with an aluminum boat builder. Though the curvature of the hull is quite different from a deep v or shallow v hull design, we know that it is indeed possible to build our boats out of aluminum. Due to the numerous requests, we are investigating the potential of having aluminum Rafnar boats sometime in the next two years.”

Inventions Shaping Our Oceans: Rafnar Hull

By Ariadne Dimoulas – This article series will look into inventions shaping today’s seascape. How has our mariner history resulted in today’s groundbreaking inventions? Which inventions direct our future? What...

gcaptain.com

Yes, exactly...I don't think they have a finished prototype yet.

 

[Unreel]

Theres a reason alot of aluminum boats have suspension seats in them.

 

[Aces]

Some excellent feedbacks. As mentioned, no issue in calm seas but pounding happens even in smaller chops. I mostly fish in calmer water anyways but time to time, we all can find ourselves in some bigger waves and choppy waters. Thank you all!

You never know when the wind will pick up and make the sea choppy

 

[staying alive]

Yes to the trim tabs makes a huge difference ,mines light gauge aluminum a 23’ Crestliner eagle , trim tabs help a lot , but some conditions you just have to back off the throttle

 

[Mike park]

I understand due to the weight, aluminum boats are more subject to bouncing. I usually add some weight to the bow of the boat and that helps. I'm also thinking of adding trim tabs to my 22' boat. Is that all I can do to help reduce the bouncing?

I had a welded aluminum Cope hull built in 95 it had a built in fuel tank under the floor in the middle of the hull. From there we filled the entire hull with spray foam , I added a plywood floor with a duradeck cover . Wave rider seat pedistals it was great.
It was quiet riding very solid and did not pound at all ,I believe getting the weight down low with the foam core was the key .
Adding floatation foam under your floor might be the answer

 

[ship happens]

Trim tabs will change your boats performance forever.

Trim tabs

 

[Mike park]

Trim tabs will change your boats performance forever.

Trim tabs

I agree 100 % and the spray foam makes the hull solid quiet

 

[walleyes]

Unless it’s in sealed containment spray foam is a no no. The amount of water that stuff holds is scary. If some remember a few years back I did a rebuild of a 16’ Lund, I documented the process on here. That boat had spray foam under the floor boards and some of the seats on the sides. I pulled two large garbage bags of foam out of that boat. The weight of that water logged foam was unreal. A half full bag of foam and you could not pick it up, it tore the bag tops. I would guess out of that 16’ boat and keep in mind this was just a little Lund so not much room from floor boards to hull bottom, maybe 6” at the thickest part but I would guess it was holding well over 200 lbs of water.

 

[ryanb]

Unless it’s in sealed containment spray foam is a no no. The amount of water that stuff holds is scary. If some remember a few years back I did a rebuild of a 16’ Lund, I documented the process on here. That boat had spray foam under the floor boards and some of the seats on the sides. I pulled two large garbage bags of foam out of that boat. The weight of that water logged foam was unreal. A half full bag of foam and you could not pick it up, it tore the bag tops. I would guess out of that 16’ boat and keep in mind this was just a little Lund so not much room from floor boards to hull bottom, maybe 6” at the thickest part but I would guess it was holding well over 200 lbs of water.

Doesn't kingfisher put spray foam in their hulls?

 

[walleyes]

Doesn't kingfisher put spray foam in their hulls?

Im not sure to be honest and not that I’m aware of. I’ve seen nothing about it in any of the build sheets or specs on the boats. And certainly not by the sounds of them lol, pretty noisy hulls.

Also the way they are set up one wouldn’t get a lot of water down into the bottom of the hull. Unless it was moored of course and the mooring top not used and the bilge pumps quit working then it would flood the boat. But by then you would have some serious issues to deal with. On the models like mine the rear deck is sealed off from the hull itself unless you pull the plugs at the back the wash catch basins it then allows water down into the bilge area. If mooring the boat I would assume this is the way it would be done.

 

[ryanb]

Im not sure to be honest and not that I’m aware of. I’ve seen nothing about it in any of the build sheets or specs on the boats. And certainly not by the sounds of them lol, pretty noisy hulls.

Pretty sure there is, but maybe they have changed the way they build their boats. Like you said foam is problematic. If it's for floatation you're much better off with Styrofoam boards (my old raider had those) or pool noodles. Always ensures proper drainage of bilge water. The spray in stuff just absorbs water eventually...but it does provide stiffness and sound deadening.

Everything is a compromise on a boat.

 

[walleyes]

Pretty sure there is, but maybe they have changed the way they build their boats. Like you said foam is problematic. If it's for floatation you're much better off with Styrofoam boards (my old raider had those) or pool noodles. Always ensures proper drainage of bilge water. The spray in stuff just absorbs water eventually...but it does provide stiffness and sound deadening.

Everything is a compromise on a boat.

Thats good could question actually Ryan. I can’t find any info on it so I just sent in a question to their tech team we will see. From what I see there is separate compartments and cells along the bottom and sides of the hull, to me they look quite sealed from each other and if they are sealed to the floor they would be in sealed compartments.

 

[Whole in the Water]

If you use foam in a boat, make sure it is closed cell foam that does not absorb water. In aluminum boats closed cell foam provides both flotation and sound dampening. Doesn't do much for lessening the pounding in choppy or rough water. To do that get: a suspension seat(s), trim tabs, weight up front and if all else fails - reduce speed.

 

[Mike park]

Thats good could question actually Ryan. I can’t find any info on it so I just sent in a question to their tech team we will see. From what I see there is separate compartments and cells along the bottom and sides of the hull, to me they look quite sealed from each other and if they are sealed to the floor they would be in sealed compartments.

I had my boat built by Bruce Cope we used floatation foam that he used, it didn't hold any water, as said it's not the only solution but part of a package with the suspension pedestals it was great, adding trim tabs would be the icing on the cake

 

[NDT]

I had my boat built by Bruce Cope we used floatation foam that he used, it didn't hold any water, as said it's not the only solution but part of a package with the suspension pedestals it was great, adding trim tabs would be the icing on the cake

How long ago was that? What model? I spoke to Bruce last year about foam in his current designs. He was against it and recommended creating air tight compartments between the bulkheads.

 

[cracked_ribs]

I've poured foam in three different boats but I would be extremely particular about how it got used in an aluminum boat.

I wouldn't pour it against aluminum directly...too much opportunity for crevice corrosion. In fact in an aluminum boat I'd be inclined to attach polystyrene or similar to the underside of the deck, and bolt the deck down rather than pour the usual polyol isocyanate stuff.

Or, if pouring, I might be interested in hitting the surface with a chromate primer, then an epoxy primer like barrier kote, then pouring the foam.

Or airtight compartments if the boat is big enough.

 

[Mike park]

How long ago was that? What model? I spoke to Bruce last year about foam in his current designs. He was against it and recommended creating air tight compartments between the bulkheads.

1994/5 when he was building boats in Parksville not sure what exact foam he used we did the floor and bow locker dry storage area with it .
I ran that boat 23 years loved it

My son is 21 in January we needed a bigger boat family is all grown up