Blast plate ?

[babybeze]

I am setting up the bottom on my 17' aquacraft and noticed some washout in the prop area. I am considering a blast plate and was wondering what you guys take on this was. I am not going to be racing more of a family hot rod but it may eventually see 600hp. Also if I do put one in how should I go about recessing it and what material should it be made of ? Thanks in advance for your advice.

[RiverRacer]

With that much power you need a blast plate or you'll be doing repairs often. To recess the bottom a router will do the job, stainless would be the way to go but you can use aluminum also!. Here's one I did a while back!..

http://www.v-driveboat.com/vweb/attachment.php?attachmentid=827&stc=1&d=1218122697

[AquaCraft]

RR,

Re: aluminum blast plate material; how thick do you like to use on a fiberglass boat like the one in your picture?

After routering a blast plate recess on a fiberglass hull; what if anything do you like to refinish the routered area with, especially around the edges that might see some flaking or peeling later on?

Thanks,

AC

[RiverRacer]

Usually they're the same thicknes as the plates. Since it's fiberglass there is no reason to finish the routed surface, it will be smooth, small nicks along the edges can be filled in afterwards and sanded!..

[babybeze]

Thanks guys. It won't be that much power to start out but its not out of the question. Next off do I need to go to a drop through strut or will a steel bolt on suffice ? Also where is the best place to get a strut ? I know its a lot of questions but this is my first total rebuild and I want to get it right. My family will be in this thing so it has to be safe. Appreciate all the info.

[AquaCraft]

Usually they're the same thicknes as the plates. Since it's fiberglass there is no reason to finish the routed surface, it will be smooth, small nicks along the edges can be filled in afterwards and sanded!..

Thanks RR!

[RiverRacer]

Thanks RR!

Any time!..;)

[RiverRacer]

Thanks guys. It won't be that much power to start out but its not out of the question. Next off do I need to go to a drop through strut or will a steel bolt on suffice ? Also where is the best place to get a strut ? I know its a lot of questions but this is my first total rebuild and I want to get it right. My family will be in this thing so it has to be safe. Appreciate all the info.

For what you're doing no need to convert to a drop through just get a good steel one, J.J. is the man for a strut 972 438 2277.... BTW, what angle is the strut you have now???..

[FC-Pilot]

Matt, is this for the boat you picked up from us? If so I would definitely agree with Art that it does not need a drop through. That is more time and money than is necessary for that boat. A good steel one from J.J. sounds like a great idea if I were you. You may want to change that shaft angle as I think it was a ten degree. Art or George would have good info as to what to change it to.

Paul

[babybeze]

Currently it is a 9 degree at least thats what the strut says (old bronze one) When I set it on the boat with the boat dead level it reads more like 8 degrees. (My cheap harbor freight angle finder is hard to read sometimes). Yes Paul this is the boat I picked up from you guys. Its almost ready for gel coat just trying to work out the details. Also on this boat there is a lot of rocker from the strut back. Its like from stut forward the bottom sits at one angle and from strut back its at another. It is flat from strut back just not the same angle. Don't know how that will have any affect on strut angle or position. Thanks again for all the info. Don't know where i'd be without this site , probably flipped over or at the bottom of a lake.

[Rattle Can Lou]

Matt, I just did a blast plate on my Rayson. A word of advice is to cut the blast plate first and if it needs to be bent do all that prior to any routing of the bottom. It will make it a nicer job. Also on the strut I would buy a bolt on and recess it into the bottom. If your going to router the bottom for the blast plate ya might as well do both. 17' Aqua Craft...fun ride.

[RiverRacer]

Currently it is a 9 degree at least thats what the strut says (old bronze one) When I set it on the boat with the boat dead level it reads more like 8 degrees. (My cheap harbor freight angle finder is hard to read sometimes). Yes Paul this is the boat I picked up from you guys. Its almost ready for gel coat just trying to work out the details. Also on this boat there is a lot of rocker from the strut back. Its like from stut forward the bottom sits at one angle and from strut back its at another. It is flat from strut back just not the same angle. Don't know how that will have any affect on strut angle or position. Thanks again for all the info. Don't know where i'd be without this site , probably flipped over or at the bottom of a lake.

Ok total brain fart here, before I make a total idiot of myself, what kind of boat are we working on here??:confused: From your description of the bottom it sounds like a carbon copy the way my Daytona was???..:confused:

[FC-Pilot]

Art, it is a normal Aquacraft as far as we knew. It is a basic flat bottom without any strakes on it.

Matt, if you decide to recess the strut down make sure to get some glass and build up the bottom of the boat on the inside. That way you won't loose much strength. I would then sand the top flat so you can do a strut brace off the the top of the floor. (I figure Art was going to say that so I wanted to sound cool and say it first).:p

Paul

[hm66Howard]

(I figure Art was going to say that so I wanted to sound cool and say it first).LOL :D:D:D

[babybeze]

This is the kind of great advice you can't get anywhere else. Thanks RCL for the tip I will definately do this makes sense after I think about it. Yes this is an Aquacraft 17' not a shark. Built heavy. Looking at the way it was rigged and a few other details I think it was meant for a marathon ski type boat. Paul, I was going to run a strut brace anyway but if I recess the base I will definately take this advice. Any idea on how large of an area I should build up ? Heres some more info if it helps. From the transom(outside) to the tip of the strut is currently 17 1/2" from the bottom of the boat to the center of the strut tube is 6 1/2". Don't know if that helps but I thought I would throw it out there. Once again I appreciate all the help.

[FC-Pilot]

Matt, for my own piece of mind I would build up an area from stringer to stringer and about eight inches in front of the strut all the way to the transom (as you are also making the area where the blast plate sits thinner to). I would sand through the old flow coat and lay a combination of mat and cloth to help provide strength that you would lose from cutting the recess.

If there is anybody that has a better idea or solution please speak up as I am only stating my opinion and don't have personal experience or testing with this.

Paul

[RiverRacer]

This is the kind of great advice you can't get anywhere else. Thanks RCL for the tip I will definately do this makes sense after I think about it. Yes this is an Aquacraft 17' not a shark. Built heavy. Looking at the way it was rigged and a few other details I think it was meant for a marathon ski type boat. Paul, I was going to run a strut brace anyway but if I recess the base I will definately take this advice. Any idea on how large of an area I should build up ? Heres some more info if it helps. From the transom(outside) to the tip of the strut is currently 17 1/2" from the bottom of the boat to the center of the strut tube is 6 1/2". Don't know if that helps but I thought I would throw it out there. Once again I appreciate all the help.

A Wickens style Aquacraft, ok cool!.. So it's a heavy layup how thick is the floor???, you may not need to do all that build up for nothing especially with a good strut support, depends on the thickness of the base also!... Strut is in the right place, but the distance from the center of the tube to the bottom tells me it's a 10 degree strut and the prop is too low that pushes the nose up, with an 8 degree angle it would raise it an 1" which would be right!.. Now about that rocker, does it start right at the back of the strut??, if you put a straight edge 3' forward of the strut is it flat all the way to the back of the strut where the rocker starts or is does it have a sag in the bottom????..

[babybeze]

It is flat from the front of the strut to almost the first fin location (little more than 3'). Front the front of the strut back it is a different angle. Floor thickness at the strut appears to be over 3/4" . I know where rudder goes through it is at least that much where the shaft log is it is maybe a little less. Nowhere through the keel is this thing less than 5/8" thick. If I go to an 8 degree will I have to redrill the shaft log hole ? Currently looking at it from bottom of boat the hole starts at 54" and ends at 64" . When you say raise o you mean bring it closer to the hull ? Sorry I know its a lot of questions and I do appreciate the info.

[NovaSS]

Art;

Is that a skid fin that I have circled in your picture or is it something else? The shape seems a little unusual to me but then again what the heck do I know :confused:

http://i56.photobucket.com/albums/g180/1969NovaSS/Blast.jpg

[RiverRacer]

Art;

Is that a skid fin that I have circled in your picture or is it something else? The shape seems a little unusual to me but then again what the heck do I know :confused:

http://i56.photobucket.com/albums/g180/1969NovaSS/Blast.jpg

Yep, it's the turn fins, a double drop through, the angle of the pic makes it look weird!..

[RiverRacer]

It is flat from the front of the strut to almost the first fin location (little more than 3'). Front the front of the strut back it is a different angle. Floor thickness at the strut appears to be over 3/4" . I know where rudder goes through it is at least that much where the shaft log is it is maybe a little less. Nowhere through the keel is this thing less than 5/8" thick. If I go to an 8 degree will I have to redrill the shaft log hole ? Currently looking at it from bottom of boat the hole starts at 54" and ends at 64" . When you say raise o you mean bring it closer to the hull ? Sorry I know its a lot of questions and I do appreciate the info.

Ok, with the straight edge sitting flat, what's the distance between the straight edge and the bottom of the boat at the transom???..

Depending on the base of the new strut you may not need to build anything up??... Yes, you will have to plug up the floor and re drill it, dropping the angle will move the hole farther forward!.. When the angle is lowered, the back of the strut will naturally move up and the front down!..

[NovaSS]

Ok, with the straight edge sitting flat, what's the distance between the straight edge and the bottom of the boat at the transom???..

Depending on the base of the new strut you may not need to build anything up??... Yes, you will have to plug up the floor and re drill it, dropping the angle will move the hole farther forward!.. When the angle is lowered, the back of the strut will naturally move up and the front down!..

that will move the Vdrive forward in the boat as well, right?

[RiverRacer]

that will move the Vdrive forward in the boat as well, right?

Correctamundo!..:D

[babybeze]

I assume by flat you mean from the stut forward if this is correct the gap at the transom is 1/2" including the recess for the plates. Plate recess is 1/4" so I guess it would be 1/4" total. Next novice question what do you use to drill the hole through the bottom of the boat ? Buzz and Paul mentioned something about a hole saw on the end of a prop shaft. If this is the way how do you attach the saw to the shaft ? Appreciate the info Art. You da man .

[FC-Pilot]

Matt, I am getting excited just with the idea that you will have to opportunity to rig your own boat. You will do great as you take your time to measure everything out. If you stick close to the info Art gives you then you can't go wrong. I will let Art get back to giving you info.

Paul

[babybeze]

Paul,
This wouldn't have been possible without you and your family's genorousity. I appreciate the chance to be doing this. I'll probably be contacting you and Buzz next spring to start talking about engine options. Wish I lived closer to get in on all the happenings out there but for now just have to look at the pics. Keep the advice coming and I will follow.

[RiverRacer]

I assume by flat you mean from the stut forward if this is correct the gap at the transom is 1/2" including the recess for the plates. Plate recess is 1/4" so I guess it would be 1/4" total. Next novice question what do you use to drill the hole through the bottom of the boat ? Buzz and Paul mentioned something about a hole saw on the end of a prop shaft. If this is the way how do you attach the saw to the shaft ? Appreciate the info Art. You da man .

Yes that is correct, but a 1/4"?? yikes!!!. Not being insulting or questioning your ability to measure, but are you sure it's a 1/4"???, do you have the boat turned over?, would it be possible to get a pic with with the straight edge on the bottom?, would like to see it if all possible!.. Yes you use a hole saw to bore the hole, you can buy one or you can make one from an everyday hole saw and some tubing!. I use an old prop shaft and turn down the threads to a 1/2" for the drill motor, drill and tap the other end for a stud to screw the hole saw on, pretty simple deal!..

http://www.v-driveboat.com/vweb/attachment.php?attachmentid=845&stc=1&d=1218343449

http://www.v-driveboat.com/vweb/attachment.php?attachmentid=846&stc=1&d=1218343449

[babybeze]

I will try to get some pics when I can get an extra set of hands. Yes the boat is turned over. Is 1/4" bad ?

[RiverRacer]

I will try to get some pics when I can get an extra set of hands. Yes the boat is turned over. Is 1/4" bad ?

It'll take a 1000hp to hold it up on that rocker, I had 3/16 on mine and it wouldn't take a set with 550hp!...

[babybeze]

Well this don't sound good. I have attatched a couple images showing the measurement and hopefully you can see the rocker in the second picture. What can I do to help my situation ?

[babybeze]

I have a theory and this may just be a rookie not knowing what I am talking about but I'm going to throw it out at the risk of persecution.With the rocker as it is it would cause the bow to want to come up (i think) and with a steep shaft angle it would drive the rear of the boat up (i think) could skip have been trying to overcome his own design when he set this boat up ? Didn't Mr. Orrin do the molds on these ? If so I would like to ask him some questions. I'm not discounting anything anyone has said as I believe every word of it. You guys go faster in circles than I have ever been in a straight line. I woul just like to know why this boat was set up the way it is and if there is anything I can do to make it better. Thanks again for all your input.

[RiverRacer]

Well this don't sound good. I have attatched a couple images showing the measurement and hopefully you can see the rocker in the second picture. What can I do to help my situation ?

Holy $hit that's 9/16" you sure that piece of wood is straight???, I see other discrepencies but could be just the angle, can you take a pic from the side?, and I would recommend using something other than an old piece of wood for a straight edge!. But don't worry it can be fixed, just like all the others!..

[RiverRacer]

I have a theory and this may just be a rookie not knowing what I am talking about but I'm going to throw it out at the risk of persecution.With the rocker as it is it would cause the bow to want to come up (i think) and with a steep shaft angle it would drive the rear of the boat up (i think) could skip have been trying to overcome his own design when he set this boat up ? Didn't Mr. Orrin do the molds on these ? If so I would like to ask him some questions. I'm not discounting anything anyone has said as I believe every word of it. You guys go faster in circles than I have ever been in a straight line. I woul just like to know why this boat was set up the way it is and if there is anything I can do to make it better. Thanks again for all your input.

Theory all wrong, but that's ok, lol. Steep angle will lift the nose making it even worse!. You gotta remember the boat is ancient and the bottom is nowhere the same as it was when new, the shape has changed over the years, the motor probably sat in it all it's life and with all that weight things are going to change, but now is the time to update it and make it right!..

[hm66Howard]

So is there any way to compensate for a sagging bottom if one is not in a position to pull the boat apart, flip it, and fix the bottom?

[babybeze]

Remember to deduct 1/4" for plates where that measurement was taken so it's only 5/16" I know thats still a lot but not as bad as 9/16". My straight edge is a peice of aluminum angle and I'm pretty sure its straight as I checked it against my level. Level just not quite long enough. Is there anyway I can fix this without adding a ton of weight in materials ?

[babybeze]

Holy $hit that's 9/16" you sure that piece of wood is straight???, I see other discrepencies but could be just the angle, can you take a pic from the side?, and I would recommend using something other than an old piece of wood for a straight edge!. But don't worry it can be fixed, just like all the others!..

I will try to get a pic from the side but there is a car in the way and my lense may not be wide enough.

[RiverRacer]

So is there any way to compensate for a sagging bottom if one is not in a position to pull the boat apart, flip it, and fix the bottom?

Gotta turn the boat over to fix the bottom, filling and sanding!.

[RiverRacer]

Remember to deduct 1/4" for plates where that measurement was taken so it's only 5/16" I know thats still a lot but not as bad as 9/16". My straight edge is a peice of aluminum angle and I'm pretty sure its straight as I checked it against my level. Level just not quite long enough. Is there anyway I can fix this without adding a ton of weight in materials ?

Wheww, that's better forgot about the plate!. Aluminum huh, ok kinda looked like wood there from the pic, make sure it is straight though, lot of angle is not accurate, I always use a piece of flat stock!... Kinda hard to tell from those pics but it shouldn't take that much to straighten it out, it sure won't a bunch of weight to it!..

[babybeze]

Ok after a good bit of evaluation on the bottom here is what I have found. Keel area has the most amount of rocker at 5/16". As you move to the port it flattens out almost perfect halfway out to the chine. Then it starts to develope a rocker again and it has a 1/8" rocker at the chine. So it appears that you are correct (as if there was ever any question on that) that this thing has sagged or taken the shape of a bad trailer over the years. Now what should I do to correct this? Should I grind down the areas that are sagged to give a true flat surface or should I fill in at the back to raise the surface up ? Or both? I appreciate all the help I really do.

[RiverRacer]

Well, I knew this all along I just wanted to know how bad it was, it don't matter how well it was fitted to the trailer, unless there is a cross member under the motor area the bunks will sag along with the boat, how long would it take for your back to sag if you had 700lbs sitting on it,LOL.... You'll have to do a little of both, you don't want to grind too much or you'll get too close to the stringers, the back you'll need to build up in layers, the rest you can probably sand and fill!....

BTW, if my boat was going to sit for a month I would pull the motor!...

[babybeze]

Okay.. after spending the last month working the bottom over and then over again I think its straight. I have less than 1/16 rocker in it now starting at around the strut area. I have also acquired a new steel strut measuring 6.6 degrees with 5 3/8" drop . So for my next round of qeustions. Where should I install the strut ? I think it was said that 17.5" from transom was good but where is it best ? Also should I try to adjust the installed strut angle by grinding the bottom of the boat for a more optimum angle and if so what would that angle be ? Just for reminder this is a 17' Aquacraft NOT the shark. Has a large cockpit area and shorter deck. It has 1" of deadrise from the keel to the chine. No strakes. Unsure of exact engine weight yet but will probably be around 650lbs. Thanks in advance for your help.

[RiverRacer]

You have a strut that's 6.6 degrees, what kind of protractor are you using, a digital??.. if it's really 6.6"???, put it in the same place as the old one, the depth is right it will keep the prop up high!.. BTW, the Shark is an Aquacraft, you just have the Wickens bottom!..

[babybeze]

You have a strut that's 6.6 degrees, what kind of protractor are you using, a digital??.. if it's really 6.6"???, put it in the same place as the old one, the depth is right it will keep the prop up high!.. BTW, the Shark is an Aquacraft, you just have the Wickens bottom!..

Using my angle finder (not digital) and also my metal working protractor (again not digital) they both measure just under 7 and the guy i got the strut from said it was 6.6 . Looking at this I will be able to run no larger than a 11" prop and that is with minimal clearance is this a bad thing ? As stated in other post I will probably be looking at 400-450hp to start. Appreciate the help.

[RiverRacer]

Using my angle finder (not digital) and also my metal working protractor (again not digital) they both measure just under 7 and the guy i got the strut from said it was 6.6 . Looking at this I will be able to run no larger than a 11" prop and that is with minimal clearance is this a bad thing ? As stated in other post I will probably be looking at 400-450hp to start. Appreciate the help.

That's more like it, 7 degree is good and so is the height you want the prop as high as you can get it, 3/8" clearance is good!. For a prop 10 7/8x16 is a good, just gear it for the power!...