Tri Hull Open Bow Deck

[Sea Stomper]

Hinged bow deck addition for a tri hull

The bow deck is essentially a large hatch covering the open bow.

The deck can be opened easily at sea or on the trailer to retrieve items like bait from the cooler or fuel the tanks.

This shows the "slide off" marine grade hinges bought at a local marine supply.

From out in the North Pacific Ocean. Off in the distance 15 miles over the horizon looking over the bow deck cover is the Humboldt Bay harbor entrance, not visible due to the curvature of the earth's surface. You can barely see some hills on the horizon.

Continued next post since I can't post more than 6 images.

 

[Sea Stomper]

Re: Tri Hull Open Bow Deck

Bow deck cover continued:

A little ocean going boat next to a bigger ocean going boat. Inn't it so cute??! This is a "proof of concept" trial season after which improvements to it will be added during the upcoming winter.



I think this will be pretty much a single post but we'll see. I haven't seen one of these built but I wanted it badly on this boat.

This tri hull is a 1977 Orrion 15 footer powered by a modified 1975 Chrysler 85. The boat is used 99 percent of the time in the Pacific Ocean out of Humboldt Bay. The ocean up here is notorious for unforgiving conditions but in the summer, it can be very nice. Much of the time I have to tolerate 7 to 8 foot seas with some wind chop, occasionally sending water over the bow on a little boat like this. It also can rain in the summer, and the open bow just collected water and drained into the cockpit. I wanted to be able to stand on the deck for fishing, launching and retreiving the boat at the ramp. I also wanted to be able to open it for full access to the contents of stored items in the bow compartment, and I wanted to be able to remove it quickly for open bow use if necessary. Stiffness was the key.

I spec'd it for 1 inch thick marine plywood fiberglassed on both sides for rigidity, air vented it for portable fuel tanks in the bow compartment, and slide off hinges. The 4X8 sheet of plywood was a little over 100 bucks. Marine grade ain't cheap. Nice wood though. After a summer in the Pacific Ocean this summer, I haven't regretted going with it one bit.

With that said, pictures pretty much tell the story. This boat is not restored and probably will not be. It is strictly a utilitarian recreational fishing boat. If a hole needs to be drilled, I drill it. No worries about scratches, I don't care. It's strictly a bang for the buck proposition and has spectacularly exceeded any expectation I've ever had. I've landed over 35 Pacific Halibut ranging from 11 to 60 pounds and numerous ocean Chinook Salmon along with a host of others. The boat was 500 bucks, the original 85 Chrysler was replaced with a 40 hour old 85 that I happened to find in a guy's back yard who I know, for 75 bucks, all fresh water time in perfect shape. That engine now has 460 hours on it, all salt water Pacific Ocean time. The boat has a rotten transom and has for the last 4 years that I have owned it. That will likely be corrected this winter but has not hindered the boat's functionality. No stress cracks anywhere in the transom. Do not take this to mean that you can safely operate a boat with a known rotten transom. This one has known good spots in it, and still has what I've determined to be adequate strength for what I do with it. Not all rotten transoms can be operated safely if at all. This decision is yours to make, so don't rely on my information here. Operate at your own risk.

It all started with the open bow boat and a piece of plywood. The boat has the hand rails removed. Hand rails are required for passengers in the front. I am not going to carry passengers in the bow compartment, so off they came. Fuel tanks are strapped to the seat bases and plumbed for supply AND remote venting. Quick disconnects to the aft supply disconnect that normally connects to the stern tanks allow feeding off of rear or front tanks. The front tank vents are connected to one rear tank vent, so all 3 vent from the same vent on the port stern tank. On this boat, either engine can feed off of any tank. I can run 6 tanks for long runs of over 150 miles for tuna if I want to. I get about 30 miles per 6.5 gallon tank filled to 6 gallons.

The sheet was set up where I wanted it and cut to match the entry door and window opening.

Side view showing blocks holding the sheet in place.

Window closed, perfect fit along the bottom.

 

[Sea Stomper]

Re: Tri Hull Open Bow Deck

Bow deck cover continued:

Trim the front corners off to match the shape of the boat.

Add a strip of the same wood, cut it to shape, mount it and install the slide off hinges.

Cut the underside filler supports to fill the gap under the deck piece.

Side filler supports installed.

Upside down on the table for glassing. Polyester boat resin was used, bought at the local marine supply. The smell went away 2 days later. I like it, reminds me of my dad building surfboards in the garage in the fifties!

Vent placement, I ended up not using the handle. It's just as easy lifting from under the deck while at sea, and using the aft vent when standing on the ground.

Continued next post.

 

[Sea Stomper]

Re: Tri Hull Open Bow Deck

Bow Deck Cover continued:

Glassing and sanding.

I used a layer of glass on top and bottom, don't remember but I think it was 6oz., and 2 coats of resin to get me through the summer without painting or putting something else over it. Like I said, I ain't a perfectionist, just wanted functionality and the wood looked kind of cool after the glass job so I left it for the summer proof of concept season. No signs of stress, cracks or wear of any sort after one season in the ocean.

Done for now, just have to cut the vent holes and install the vents.

Son Cameron after a very successful ocean salmon fishing adventure in the evil North Pacific!

End

 

[zopperman]

Re: Tri Hull Open Bow Deck

Very nice addition.

I'm surprised that little tri hull can handle 8 foot seas

Good luck with the transom. We're here to help if you need it.

 

[Sea Stomper]

Re: Tri Hull Open Bow Deck

Believe me, I was surprised it would handle 8 feet too, but that's max I'll deal with. Tri hulls are amazingly sea worthy but you wouldn't think so because of the low freeboard. I seldom take water over the side drifting powerless for halibut in 6 to 8 foot seas. If you think about it, the boat is much like a small piece of wood floating over big waves. In fact, if it was a 20 foot swell with a long period, it would be no problem either, just really really scary! The stuff it has trouble with is 2 foot breaking white caps.

 

[jarrpal001]

Re: Tri Hull Open Bow Deck

hi sea stomper
what made you choose a trihull and not a v-hull? what do you mean by very stable and they dont get into rolling problems?
when i saw your boat and read your messages i told myself this is the guy that i have to get to konw.
one thing i like is when im fishing the boat is really stable. not rocking from side to side if my buddies or me are walking on it.
the ride is something else. not to bad but it does take a pounding when its choppy. is there anything i should watch out for or be worried about when the waters are choppy. i dont know a whole lot about boats especially tri hulls. i took the classes and learned a lot but mostly everyone in the class had vhulls.
any advise will be deeply appreciated.
just to let you know i live in florida between orlando and tampa. ton of lakes, bays to my left and ocean to my right
thanx.

 

[xanthras]

Re: Tri Hull Open Bow Deck

Looks like a great addition. Very functional. I would personally paint it white or something.

 

[Sea Stomper]

Re: Tri Hull Open Bow Deck

Yea, I am going to paint it. It's going to get a splash rail or two and the windshield will be raised a little this winter, so I left it unpainted for this season. Not done yet. Thanks for the suggestion.

As for choosing the tri hull, I didn't really choose it. It kind of fell into my lap. I'd rather have a V hull but I had an old Ford Bronco II that I needed to get rid of and a guy at work had this boat, so we swapped. Tri hulls are stable not only sitting still or trolling at slow speeds, but they are VERY good in following seas in the ocean because the outer hulls keep them from rolling and they don't broach very easily. That means they don't tend to roll away from a forced uncontrolled turn when pushed from behind with a swell or while riding the face of a swell when you hit the trough of the swell. So they go straight ahead, and are self stabilizing going with the swells. However, as would be expected, they suck going into the swell because of the obvious pounding problem of the flat hull shape. On this boat it has been minimized by the weight of the two fuel tanks, the bow deck, and whatever else goes up there, usually the bait cooler and ice in it. That acts like a trim tab where the bow will follow the contour of the swell instead of trying to launch into the air at the top of each swell peak and has the added benefit of increasing fuel economy because it planes so easily also with the addition of a Doel Fin on the engine cavitation plate. The bad side of weight in the bow is that you can dive into wave faces and that gets you all wet. I dove into one this summer that came into the open cockpit cover flap and got two of us completely wet at 5 in the morning.

So the tri hull wasn't really a preference, but I discovered some really nice things about it and as a result, I don't think I'll be getting rid of it for a few more years. It's so reliable, so cheap to operate, and so well behave at sea. Why spend money on a bigger boat? The Chrysler was modified with a Mopar ignition box triggered by the original electronic Chrysler Outboard distributor "optical interrupter" style unit I forgot the name of, connected to an MSD Blaster coil with L86C racing plugs. No fouling and very cheap to replace parts AND you can run an automotive tachometer switched to the 6 cylinder position running on this 3 cylinder 2 stroke (same number of ignition events on a 3 cylinder 2 stroke as on a 6 cylinder 4 stroke for every crankshaft revolution).

The older Boston Whalers that still hold their value are pretty close to a tri hull. There are two or three other tri hulls out of Humboldt Bay who use them in the ocean. Tri hulls are sea worthy if you have a good dentist (as in they jar the teeth out of your skull!).

 

[fstorm08]

Re: Tri Hull Open Bow Deck

Looks GREAT!

Do you get much water through the forward facing vent when the seas are a bit rough?

 

[Sea Stomper]

Re: Tri Hull Open Bow Deck

Hi fstom08, yea, I was a little concerned about that. It so happens that it's not very often that water comes up over the bow, so when it does, it's very seldom and the stuff getting in through the vent never really is a bother. What was a bother was when there was nothing covering the open bow. The sea conditions that get water over the bow are when it's very windy with white caps and 3 foot wind slop. When it gets like that, I HEAD FOR THE BARN! You can have 7 to 8 foot seas on glassy windless days, slowly rising and falling on the swells passing by and it can be quite pleasant. I hate the windy white capping stuff though.