Building my first boat.....

[Harrison1010]

Hello all, have been reading for a while now. Have learned alot but i need alittle help. Im currently building a 13 foot boat, out of plywood. This is my first attempt at a boat and wanted to design it myself. I will be posting some pictures soon. I have the hull put together and used a bit of a stitch and glue and framed construction. The inside is going well im building sits and all right now, and am planning on flipping the boat over soon and glassing the bottom. I believe i have made way to much of a deep V, and i thinking stability will be poor when its sitting still. Im on a budget and am really just having fun building the boat. My question is... Is there any way to improve stability during my glassing time while the boat is flipped over such and adding foam around the stern on port and starboard just before or right after the chines? or any other ways to improve stability? Thanks for help

[lewisboats]

just how deep did you make it? How wide is it from chine to chine and how deep is the vee from the line running from chine to chine. For example... 6" vee depth on a 45" waterline beam comes to 15 deg deadrise...I would consider that a medium vee. Below is an example of 15 deg deadrise on a 14.2 ft LOA (12.365 ft LWL) boat with a max beam of 5ft (23 deg flare). Additional stability comes from the angle of the flare of the sides...the more they flare the more stable they get as you heel and also as the boat is loaded down (like a Dory). The Freeboard or amount of Side above the waterline is also a factor when the boat is heeled.. A longer boat is also more stable than a shorter boat...so is the boat 13 ft long overall or 13 ft along the waterline? Lots of factors to consider here. I see that you are on the left coast...are you planning to use this in waves and if so how high? A vee will help cut through swells and may even ease the motion compared to a flat bottom or shallow vee but a 13 ft LWL or LOA boat is a pretty infinitesimally small speck on big water though and subject to whatever it wants to do with you.

Steve

[robherc]

If you get out on it and find that it's too unstable for your tastes (PLEASE test that while within easy swimming distance of a shore), you can make small floats out of foam, or plywood, and attach them in a trimaran configuration. If you attach them directly to the sides of your boat, though, they may add significant drag. Better to put them on short akas (arms) so they're at least a foot or two away from the main hull, this way they'll be able to give much more righting-moment per displacement (so you can make them smaller/cheaper), and they'll interfere less with water flow around your main hull (if you place them too close to/touching the main hull, there may not be enough space for all of the displaced water to flow through between, then you've created a "sea anchor" of types).

The above are my opinions, not professional advice; regard the information accordingly.

[alan white]

It may be better next time to design the boat before, and not during construction, but at least you will learn the best way, which is (as you now see) the hard way, how to go about a boatbuilding project next time.
If you show a midship section here for people to look at, you'll get some idea what remedy will save your project (if it needs saving, of course).
It is possible, for example, to make a flat bottom panel after removing the pointy bottom you claim to have now.

[PAR]

Second guessing stability during the build, is generally not the best way to go about designing boats. If you feel she's going to be too tender, then you could convert the bottom sections from a constant deadrise (I'm assuming that's what you've got) to a warped bottom. Foam attached from say about midship aft to slowly decrease the deadrise, which will provide more stability, plus permit the boat to get on plane faster with less power. Of course, you need to understand how and why you're doing this, which appears, from your initial post that you're not sure about. Without some line drawings of your hull shapes, it would be next to imposable to offer much more advise.

[Harrison1010]

Thank you all for the input. Yes i do regret building it this way, but it has been a blast and a great learning experience. I was initially wanting a wider boat so i figured i could go with a deeper angle. Please understand this is an experiment and im having alot of fun, im trying to stay in a budget and taking in as much as i can from this. I can already see when i build my next boat i am going to do things ohhh so differently. Anyways here are some pictures where i am at now. The holes in the seats are where the doors for the little cabinets will be. Up forward i plan on closing it off half way to add support and have more storage....So stability? how am i looking? How to help it? Could adding a outboard bracket that is like 6 inches thick running the width of the boat help, if keep flat and filled with foam? just an idea. any thoughts or suggestions on the entire boat is welcome. Please dont tell me to throw it away and start over

[Harrison1010]

Sorry, here are dimensions: chine to chine 56", width of boat at top of gunwale 64" height of gunwale 18", boat height at stern 29", if i draw a line from chine to chine its 11" 1/2 to bottom at the center of the boat. width of the panels making the V is 30", with an overall length of 12'7". Hope that helps.

[robherc]

Looking at the pictures, I THINK you'll be able to get away with it as it is. She might be a little "wobbly," but I think she'll stay upright for you. Planing might take a little more power with that deep "V" though, but I'm just guessing there....I'm DEFINITELY NOT an expert on planing hull-forms, so i'll let someone else give you a more definitive opinion there.

[Manie B]

That is an extreme example of a very very deep "V"
in my opinion it is way over the top for such a small boat and the boat will be so unstable that it will be a dog

this is only my opinion and i am trying to give my 2 cents worth - i am not trying to start a war

do your self a favour and get the boat to swimming pool AS IS - do not put any more work into it before you have done a swimming pool test - my prediction is that you may want to discard the boat after you have tested it in a swimming for TWO MINUTES

I built a similar sized FLAT BOTTOM last year that works well and is being used every weekend. It goes well with a 5 hp Mercury two stroke, and is remarkably stable for such a small boat - but do remember it is a flattie

[PAR]

You could add some chine flats, which would improve initial stability. I’d make them fairly wide, at least 6"

A profile shot would be helpful to determine the amount of rocker, what the run looks like and chine shape, plus an over head view to see the sweep of the chines.

I think your transom cutout is narrow and the hull will surely be tender, without modification. It’ll also need a fair amount more HP to get her up on plane then a similar size, more modest V hull.

[lewisboats]

Ya...that's pretty deep...about 22 deg deadrise. Is the transom angled backwards or not and if so...by how much? I did up a quicky model in Freeship to give you an idea of what it might look like on paper. I raked the transom by 15 degrees which will accomodate most motors but it looks like yours doesn't have rake to it. I also didn't add a forefoot because I can't see one in your pictures from the angle they were taken. For one foot of draft...sufficient to get the chines damp and into the more stable zone you would have to have it displace from 1400 lbs in fresh water to 1500 lbs in salt...pretty darn heavy for a 14 ft LOA motorboat. give a few more details so I can refine it more. It always helps to look at a linesplan when getting opinions from folks. Like PAR says...a shot from above would help with the chine shape and a shot from the side...from at least 20 ft away and about level with the shear would help immensely. If you can't get one from above...a shot of tis bottom while it is on its side would be fine.

Steve

[ancient kayaker]

1010, how about sketching the plan, profile and stations (cross-sections) at stern, transom and a couple of feet back from the bow. There's some serious design know-how looking at this thread, and the forum guys are the most helpdful bunch you could hope to meet.

While not an expert I have reservations about durability of construction. The chine seams look weak and I would think the bow needs beefing up. Also the sheer looks practically flat, which might cause a lot of water to come over the bow if you are butting into some chop.

In my early days I had the same approach, never mind the design, just build the thing. Stability was the big problem. I ripped the bottom out of my first boats at least three times and put in new ones during the learning experience, it wasn't that difficult to do although they were smaller than yours.

My idea would be to take out the middle 50% and put in a flat bottom, tapering it to a point aft of the bow but wider towards the stern. It should remove bouyancy from low down, allowing the hull to settle lower in the water in increasing the waterline beam without heaps of ballast, and maybe raise the bow a bit. Might even plane.

What do you think guys: can he save her?

[Harrison1010]

Ancient, thats sounds like a good idea, i could taper it back from about 5 feet back from the bow. I will add more pictures soon. I have to borrow a camera to add pictures. I'm really hoping i can save her. Yeah i know what you mean about planning it out. I was going to go off a plan, but i wanted to practice my skills so i figured i could go a cheap route. I have really enjoyed it cause i can constantly think about the design and i always think of different ways i could have done it. Next time will be more of the "show boat" and i will go off some plans or really plan my own out well. anyways thanks for all the help and suggestions are welcome. I want to add a compartment at the bow which should give it more support.

[PAR]

Without a side and overhead shot, I'd be guessing, but I suspect chine flats, possibly with a "pad" may work. Lets give him a chance to post some pictures, so we can have a better idea of what's going on.

Ideally, you don't want to add to the displaced volume and subtracting would be very beneficial.

How much engine are you going to toss at this?

One simple way to improve stability and decrease volume would be to literally lop off the lower portion of the V and put a flat panel in it's place as Ancient kayaker has suggested. The keys will be where to start this butchering, how wide and how much volume.