Bulbous bows

[Jaysen]

Because of the beaching and likely need to repair, I’d be inclined to foam the top before the are installed. Seems like it could get complicated so I’ll assume it’s a bad idea.

[fallguy1000]

OK, I am starting to ‘get’ it!
Don’t take this question the wrong way, as I am genuinely curious.
Does the need to undertake this mod reflect an issue with the original design, or did you inadvertently make it bow heavy during the build. The front-on pic highlights just how fine the bows are.

It is a 'fine' question.

There are a combination of factors, but when the designer asks you where to put the water tanks; that is a deficiency of design. I moved them 17 feet back and reduced them from 53 to 36 gallons.

The solar panels are 106 pounds and about 3' past lcg for a moment of 318ftpds for'd.

The netting beam was purchased by accident at 1/4" wall instead of 1/8" wall, a moment of about 20 pounds at maybe say 13 feet or 260 pounds.

The cabin has tempered windows which are heavier than acrylic. Maybe about 5' and let's say 40 pounds heavier than light acrylic..200 ft pounds.

My LCB and LCG are off by about 9" iirc. I can come up with about 4" of changes. BUT! The axebows are so fine the anchor cannot be kept on a bow pulpit as its moment too great for the vessel. Now, the anchor is going to be on a shorter pulpit on the netting beam..

So, this is really a matter of design. There are a few places my boat got heavier in the cabin..Changing them is nearly impossible. The cabin or bridgedeck has two soles to provide a vee. This really cranked up the vessel weight and reduced the bdeck clearances. It is basically two layers of one inch plascore with a lot of fiberglass. I would guess the bdeck sole weight
To be about 300 pounds. Had the design given me a lighter means that was also strong enough; that would have helped.

I placed propane and diesel heating system tanks forward of lcg. Also, an error. But was it? Those are 3 nice big lockers. Are they designed to store air?

Anyhow, this is a design deficiency. The bows need to be fuller.

All easily attainable by switching the nose to a crash cone and opening the geometry up front. I only needed 0.15M^3 or 660 pounds of displacement. Had it been done with the original design; it'd also be much lighter..the part i am making is meant to take a log strike..

My engines are 240 pounds overweight. This offers a moment of say 15'x240 or 3600 foot pounds which should have offset everything above!

If it were not for the engines being so overspec; this boat would be down by the bow maybe 15"!

[rick berrey]

fallguy , I think you also mentioned once that you used mat . I think with today,s modern material,s that mat should be replaced and avoided in a build if possible . The cost factor in replacing mat with another fabric is probably offset to some degree by epoxy savings . Weight savings from replacing mat on a 5500 lb displacement boat should be around 200 to 400 lbs . That would not have brought the bows up in this case but would have been another thing that would have helped out . If you used mat fallguy I would like to hear any negatives on mat and your thoughts on replacement where thickness or puncture resistance is needed . Thanks

[Jeff]

Nice work FG!!! Jeff

[rick berrey]

If you have any scrap foam you could fill in with and then use some pour foam to tighten it up and bond the scrap , at least in the forward voids .

[rick berrey]

Or better yet build you a small form of the forward void and fill it with pour foam , remove it from the form , trim it up and place it in the void , that way puts no pressure on the Bulbous bows .

[fallguy1000]

fallguy , I think you also mentioned once that you used mat . I think with today,s modern material,s that mat should be replaced and avoided in a build if possible . The cost factor in replacing mat with another fabric is probably offset to some degree by epoxy savings . Weight savings from replacing mat on a 5500 lb displacement boat should be around 200 to 400 lbs . That would not have brought the bows up in this case but would have been another thing that would have helped out . If you used mat fallguy I would like to hear any negatives on mat and your thoughts on replacement where thickness or puncture resistance is needed . Thanks

Yup; used mat glass, penalty was 300-400 pounds, but the entire hull gets the penalty. It ain't reserved for for'd areas.

If I started over 1208 tapes would have been discussed and saved back the weight..

The tapes are handier because they hold their shape
So well.

[OrangeQuest]

With a lot of the forward part of the hull wanting to part the water more than it wants to stay on top of it, the bow will be very weight sensitive. The bulbous bow addition should correct that. That is my guess.

[fallguy1000]

Today, I recut custom tapes for the bulkheads.

Uff da.

Hours on my feet. But kitted the set for BB#2...

Two bulkheads left to cut and tomorrow need to laminate the 2nd backbone.

See if I can get back to my schedule. I am behind now for tape cutting not on the plan.

[Fuzz]

Not sure how this is going to work out for you but..........................I know of about 50 boats that have added them in the past few years and none of them have had them removed. It is my guess this is going to make things much better.